Eye-popping chart from RBC (via the FT) showing the dominance of 4- to 6-year Treasuries by the Fed after quantitative easing. Essentially, it's full of Fed. http://paul.kedrosky.com/archives/2010/10/treasuries_its.html
Incidentally, there's been chat that they're potentially going to buy 30s this time arnd. Probably wishful thinking on behalf of some mkt participants.