im thinking the trinity cpu's will dual up with a 7770 since there is no 7600 series, its a rebrand of 6600... it wouldnt make sense for amd to upgrade the cores on the apu, increase its speed, and then market dual graphics for an obsolete set of gpu's? if it does use the 7770 its going to be pretty quick!
the 7660D is the name of the int gfx in trinity. you should be able to pair it with the 7700 series cards in dual graphics
This looks pretty damn awesome to me. http://hexus.net/tech/news/cpu/38533-amd-trinity-a10-4600m-benchmarks-revealed/