If I'm not mistaken, PA6T is a mobile PPC970 ... and IIRC, PPC970 is a Power6 stripped and modified for desktop?
So it is not generations behind, even if it runs circles around (PA6T might be better in performance per watt).
Nope, PA6T is a completely different design to the PPC970.
The PPC970 was derived from POWER4 IIRC.
Power7 is a very nice chip, but the closest we will get to it as consumers will probably be a next generation console, if any of them use the basic core in their designs (i.e., WiiU, XBox720 - PS4 is most likely x86 according to the rumours).