Seems to be speculation at this point, but it makes perfectly logical sense.

============== Where does a team of engineers of this calibre go when they are not really welcome at AMD or Intel? Easy, greener pastures was not a euphemism, they went to Nvidia. What are they doing at Nvidia? Well duh, they are making a CPU.

The ATI buy put Nvidia is a really tough spot, it either has to make a CPU, change its entire product line, or wither and die. Given the egos involved, the first one is the only real option, not that they haven't threatened it in the past.============

There's several other links there, dunno if it can be confirmed but it makes for good forum chatter, no?