AMD confirmed it a few days ago the 4870 has 800.
nVidia answered by dropping the price of the 260/280. Also their mystery card is still a giant question mark. Could be very interesting what will happen.
Things to factor in.
Intel's Nahalem currently wont support SLi but this wont effect cards like the 9800GX2 or future GX2 models due to the SLi being run through software and not an motherboard installed chip.
possible 9900 cards
wtf the G100 will be
The HD4900 (without AMD, ATI would so dead now, ATI lovers should love AMD for their support in fixing the Radeon series)
if nVidia gives Intel the SLi chipset.