Particle as to your response about the TDP ratings. You will notice we said AM2+ and AM3, they are both desktop chips so it is nothing to do with that.
The server socket is different, though I prolly expect some 1P AM3 chips eventually.
There is still a difference between the AM2+ and the AM3 desktop chips rating ACP/TDP at the same speed. The only things I can think of is 1) better stepping for AM3s or 2) In DDR3 mode the IMC uses less power? or 3) Or higher power on the AM2+ chips because they have to support a single power plane and work in AM2 mobos. All seem a little odd.