Nope, it's true.
This link has a synopsis of many of these cases and often has scanned court documents of the actual indictments.
Did you look closely at that synopsis? It consists of:
6) 6 people (Mohammed Salameh, Nidal Ayyad, Mahmud Abouhalima Ahmad Ajaj, Ramzi Yousef and Sheikh Omar Abdel Rahman) who were sentenced to life in the 1993 WTC bombing. Presumably they are still in jail.
-) Abdel Jabbar Hamdan who was released in 2006. (
http://www.npr.org/templates/story/story.php?storyId=5620739 )
-) Abousfian Abdelrazik*who is living in canada (and not in jail)
-) Adnan el-Shukrijumah*who is still at large.
-) Ali Abdul-Karim Farhat and Hassan Farhat, who were arrested for cocaine distribution (not terrorism).
-) Ali Hasan Abu Kamal who killed himself during his act of terrorism.
-) a lawsuit (Ashton vs al Qaeda Islamic Army) filed against 3 islamic organizations that put no one in jail.
-) a lawsuit filed by the parents of David Boim who was killed in a Hamas attack on the west bank which put no one in jail.
-) Cedric Carpenter and Lamont Ransom who were convicted 2005 of selling false documents to members of a terrorist group. Since Ransom's sentence was only 29 months he's undoubtedly a free man. Carpenter's sentence was 63 months, which given the time already served at the time of conviction may mean he's also now out of prison.
-) a lawsuit filed by victims of a Hamas attack that put no one in jail.
-) a lawsuit by victims of 9/11 against the Saudi government that put no one in jail
7) Ghazi Ibrahim Abu Maizar convicted in 1999 of plotting to explode a bomb in a New York Subway. Life in prison so I assume he's still there.
-) a treasury press release regarding a terrorist organization (sorry, no one is in jail as a result)
-) Hamaas Abdul Khaalis (somewhat of a cult figure and with no apparent affiliations with foreign terrorist groups) and 11 other armed men seized buildings and murdered hostages in Washington DC in 1977 (not 1997 as your link indicates). When they finally surrendered, all were charged
then freed on their own recognizance (believe it or not). All were later tried and convicted with Khaalis receiving a sentence of from 21 to 120 years. However, Khaalis died in prison in 2003. The other 11 who all received similar lengthy sentences (
http://middleeast.about.com/od/religionsectarianism/f/me090310a.htm ) may or may not be in prison at this time … 33 years later. You know how that works. In any case, it's kind of hard to call this a terrorist case to justify Holder's claim since it's difficult to imagine Holder including this case in his list of terrorists that we still have in jail. If he did, he must be dredging the bottom of the barrel to arrive at his 300 number.
-) Hatem Fariz pled guilty to assisting the PLO. He was sentenced to 37 months back in mid 2006, so with that date he must already be out of prison.
-) Hesham Mohamed Hadayet who killed tow Israelis at LA Airport, then was himself killed.
-) a lawsuit against another terrorist sponsoring organization (Holy Land Foundation) that put no one in jail but blocked it's assets.
12) Bayan Elashi, Ghassan Elashi, Basman Elashi, Hazim Elashi, and Ihsan Elashyi who were convicted of laundering money for Hamas and received sentences from 4 to 7 years back in 2004-5. Ghassan Elashi and two of his brothers were later convicted and sentenced in a second trial to even longer prison terms. I imagine all 5 are still in US jails.
-) a lawsuit brought against Iran by family members killed at Khobar Towers. No one went to jail.
-) a lawsuit against the Islamic Center of Tuscon. No one went to jail.
-) Ismail Selim Elbarrasse arrested because his wife videotaped the Chesapeake Bay Bridge from their SUV. No one in jail.
-) Jamil Abdullah al-Amin is a black panther member found guilty in the murder of a sheriff deputy. Hard to imagine Holder labeling this a terrorist.
-) lawsuit against another islamic charity, KindHearts. No one went to jail.
-) Majid Mahummud al-massari deported and not in jail.
13) Muhammad Salah and Abdel Haleem al-Ashqar were indicted and sentenced for Hamas related racketeering in 2004. Salah was sentenced to 21 months and is now free, Ashqar was sentenced to 11 years. Presumably he's still in prison.
-) Mir Aimal Kasi killed 2 CIA employees outside Langley. Convicted and sentenced to death. Executed 2002 so not in jail.
-) Mohammad Momin Khawaja found guilty of a foiled bomb plot in Britain. Sentenced to 10 years and 6 months in 2009 IN CANADA.
-) lawsuit against insurance company AIG for promoting Sharia law and charities. No one went to prison.
14) Naveed Haq guilty of first degree murder in 2006 shooting at a Jewish organization building in Seattle. Life sentence but do you really think Holder is labeling this terrorism given the Obama administrations reticence to even use the word terrorism? But what the heck, I'll give you this one.
-) lawsuit against CAIR. No one went to prison.
-) lawsuit against the Palestinian authority. No one went to prison.
-) lawsuit against the PLO and PA. No one went to prison.
-) description of a memo related to terrorism. No one went to prison.
-) Raed Hajazi convicted in absentia IN JORDAN, caught and sent to a Jordan prison.
-) lawsuit about requiring visitors from arab countries and North Korea to register. No one went to prison.
-) suit by professor against Homeland Security over revocation of his US visa. No one went to prison.
15) Rashid Baz attacked van full of jewish boys. Convicted and sentenced to 141 years in prison. I'll give you this one too.
-) lawsuits by americans wounded in Hamas attacks against terrorist organizations. No one in jail as a result.
-) lawsuit against the SAAR network. No one in jail.
-) Safia Jilani charged with making a false police report about a masked gunman she said assaulted her. Not terrorism or in jail.
-) lawsuit against the PLO. No one went to jail.
-) Houssein Zorkot charged with carrying a dangerous weapons with unlawful intent. He received probation, not jail (
http://www.debbieschlussel.com/4135...w-ak-47-goes-free-may-be-medical-doc-in-mich/ ).
16) Abdulhakem Mujahid Muhammad shot 2 soldiers in Arkansas and charged with murder and terrorist acts in 2009. I bet he's in jail.
17) Taheri-Azar drove jeep into crowd of students. Sentenced to 33 years in prison.
-) lawsuit against Lebanese banks. No one in prison.
-) Akram Musa Abdallah plead guilty to making false statements to the FBI in 2009. Under supervised release (i.e., not in prison).
18) Rahmat Abdhir indicted for providing support to terrorist. In jail awaiting trial it appears.
19) Nurandin Abdi sentenced to 10 years in 2007 for conspiracy to blow up mall.
-) Mohadar Mohamed Abdoulah charged with lying on application for political asylum, not terrorism.
-) Abdow Munye Abdow in October 2009 charged with making false statements to the FBI, not terrorism, even though the case appears related to terrorism. He's free awaiting trial.
20) Umar Farouk Abdulmutallab chared with Christmas bombing
21) Ahmed Omar Abu Ali convicted of providing material support to al-Qaeda and attempting to assassinate the President. Sentence to 30 years.
22) Hassan Abu Jihaad sentenced to 10 years in 2009 for supporting terrorism
-) Babar Ahmad indicted in 2004 on conspiracy to aid the Talaban. Presently in a British prison.
25)Zubair Ahmed and Khaleel Ahmed pled guilty to providing terrorists material support in 2009. Both in prison.
27) Syed Ahmed and Ensanul Islam Sadequee charged with aiding terrorists. Sentenced to 13 and 17 years in prison.
28) Syed Talha Ahsan charged with maintaining jihadist websites and aiding Babar Ahmad. Case pending in the US.
-) 11 Dearborn Michigan people charged with racketeering related to cigarette smuggling scheme that helped Hizballah. In January 2004 Mohamed Akhdar, the ringleader, got a 70 month sentence. So by now he and the others are out of jail.
-) Sami Al Arian pled guilty in 2006 to helping the Palestinian Islamic Jihad. Sentenced to 57 months but given credit for time served so only had to serve 19 months. Then subpoenaed to testify in another grand jury. Received to testify and charged with criminal contempt. Under house arrest awaiting trial (http://en.wikipedia.org/wiki/Sami_Al-Arian ).
-) Al-Badawi indicted for role in USS Cole bombing. Tried for same in Yemen and sentenced to death in 2004. Escaped from Yemen prison and currently at large.
-) Sami Omar Al Hussayen, charged with helping Hamas and jihadists in 2004. Acquited of all charges and deported. Not in jail.
-) Sheik Mohammed Ali Hassan Al-Moayad and Mohammed Mohsen Zayed charged with aiding al-Qaeda and Hamas. Pled guilty and judge sentenced them to time served and deported them.
-) Saleh Al Suwailem, charged with threatening to place explosive on plane. Charges dismissed and he was released in 2006 (http://new.accessnorthga.com/detail.php?n=120237 ).
29) Ali Al Timini convicted of inciting terrorist activity and sentenced to life in 2005
-) Muthanna Al-Hanooti accused of spying for Iraq under Saddam Hussein. Not terrorism related.
- lawsuit against al Haramain Islamic Foundation and two employees for bank fraud, tax evasion and money laundering. The trials still going on and from what I can gather the two employees are free on bail.
OK, I tire. I'm almost a third of the way through the link's summary and the total number of terrorists in US jails in that third looks to be 29. So using that as a sample, I'll predict the total is around 100 for the whole list. If so, you still have several hundred to account for. 
Now you don't suppose Holder and the rest of the incompetents in the Obama administration are getting their claim of 300 terrorist now in jail from this:
http://www.washingtonpost.com/wp-srv/nation/dojstats/full330.html
June 12, 2005
330 Suspects Charged
