To be honest, what we're seeing here from yeti101 (and, from a lesser extent, from lionking) is a form of diversion I'm quite familiar with when speaking about the case with those of the pro-guilt orientation. When it comes to discussion of the evidence of the case, switch the discussion to the "confession"/"false accusation"/whatever. Interestingly enough, this line of inquiry is not pressed in the sense one might expect, as "well, why should there be any doubt of guilt, since Knox herself confessed?" Instead, emphasis is placed on the "false accusation" aspect, as a way to portray Knox as having freely tried to get someone she "knew to be innocent" punished for the crime.
In fact, it's back to arguing the case, not on its merits, but on the supposed bad character of the defendants -- much as the "dirty-souled, she-devil, spell-casting witch" rhetoric does -- by implying that one or both is such a bad person that they well could have committed the crime. After all, if you'll willingly commit perjury and try to get an innocent person punished, why wouldn't you commit murder without a second thought? And, if you can plant the idea in people's minds that these two were conscienceless enough to easily commit murder, it becomes much easier for them to imagine them doing so, and deciding that said imagined scene is what really happened.
But, in fact, that is an illegitimate way to decide a criminal case. (Although, ironically enough, it has a certain parallel in the supposed actions of the Perugian police during the investigation -- repeatedly telling Knox that "they knew" the murderer's identity, and inviting her to "imagine" what might have happened, until she agreed to it herself.) A criminal case should always be decided on the evidence itself...and, at this point, there's virtually none left standing to implicate Knox or Sollecito, but a vast amount implicating Guede and only Guede.
If the evidence isn't present to convict, the character of the defendants should matter not at all. It shouldn't make a difference if Amanda Knox was a Mother Teresa or a Mommie Dearest. Even if she was the most evil person on earth, if the evidence doesn't prove that she was in that room and stabbed Meredeth Kercher to death, then justice requires she be acquitted. The same goes for Sollecito as well. If there's a further issue with either or both of them making false statements to police, there should be a further criminal process related specifically to that charge, and, if found guilty, they should be sentenced to the proper punishment for that offense (fortunately for the defendants, Italian law -- unlike yeti101 -- mandates far less than forty years). But it is a legal absurdity to punish perjury with a murder conviction, or to imply that a person's alleged character, and an alleged propensity to be willing to commit a given crime demonstrated by that character, should be sufficient for conviction, in the absence of convincing proof, beyond a reasonable doubt, that they actually did commit that particular crime.
In the USA, the prosecution makes the first closing argument followed by the defense BUT then the prosecution and ONLY THE PROSECUTION makes a rebuttal argument. The reasoning is the prosecution has the burden of proof and must prove its case beyond a reasonable doubt. 
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