The Inquirer heard from their sources that AMD is having voltage problems with their 65nm processors:
This is forcing AMD to pump things as high as 1.4V. If you do the math, (1.4^2)/(1.1^2) = 1.62, so AMD is forced to use 60+% more power than they wanted to. This kind of skews the performance per watt leadership they are claiming, so I guess there is still work to be done.
That said, there is a bit more than three months to go before any deadlines are missed, and the wafers going in today are still not the ones you may end up buying, so there is time. Barely.