Based on the various market information (a.k.a, "rumors"), and most importantly, the recent performance of Gold and Oil, it is safe to conclude that Fed will announce QE3 no later than Q2 2012.
The time frame will also accommodate Obama's campaign for re-election.
I think the Fed will announce it when Greece defaults, or something really bad happen. QE3 is weapon of mass destruction, would only us it when is needed......but I do think is just a matter of time, because Greece will fefaults.