A pretty good read. Covers the hilights of a lot of different Internet coverage of the case.
Well you brought it up!

The below is all TheL8Elvis's fault.
Apparently the people in the massive Zimmerman case thread(s) at justicequest.net seem to think they have found one of the prosecutions secrets.
It seems they have been talking about this for days now, I'm surprised I haven't seen it here at the JREF yet. (Unless I missed it here...)
Warning: That forum is the exact opposite of the conservative tree house place. Read both of those forums and you will see the the polar opposites that show us that the JREF forum is really the place for the skeptical middle ground.
Warning: This happens exactly 4 seconds
before what we previously refer to as the flashlight taps. Take that for whatever it is worth.
Apparently in the not911 call they say Z does a "chamber check" on his Kel-Tec after being asked what his last name is.... This happens very late in the call, 30 seconds after Z gets out of his truck, and 15 seconds after he is told that the not911 does not need him to follow M.
They seem to think there are a boatload of reasons why it would not be good for Z if the prosecution can prove he had his gun out. I only seem to think there are a few. Anyway...
I believe it happens around 2:10 in this YT of the not911 call:
http://www.youtube.com/watch?v=6aVwPqXc-bk
There are 5 files in the below .zip.
http://wikisend.com/download/327374/chambercheck.zip
01 is Z's supposed "chamber check" from the not911 video
02 is a supposed Kel-Tec demo vido with a "chamber check" at the very end of the clip (after he says "see how they do").
03 is the Z "chamber check" isolated
04 is the Kel-Tec demo video "chamber check" isolated
05 is 03 and 04 ran back to back for 10 seconds
----------------
My personal conclusion? I am not convinced..
Points against = They do not sound exactly the same.
Points against = I have no idea of the validity of the supposed Kel-Tec demo audio. Or even if the sound that we are even being presented with is a feature of that gun.
Points for = The audio of both clips is from different sources, so they have different variables. Which means they should not sound exactly the same by default. So that may be why one of them sounds much "crisper".
Points for = Is it a coincidence that he had the same gun and we hear a similar sound? What are the odds of that?