We spotted some GeForce 8800GT benchmarks over at the Mobile01 forums, altough we can't verify that they're the real deal and the 3DMark screenshots look slightly odd.
Aparently the upcoming 8800GT will score 14679 in 3DMark 05 and 35351 in 3DMark 03, but the odd thing with the screenshots is the fact that the CPU is reported as @ 2400MHz which makes it all look odd.
A bit more reliable is the cut-out from some Nvidia material which talks about clock speeds and stream processors, as we already knew the cards would have 112 stream processors and according to this info they'll be clocked at 1.5GHz.
The cards will also have a 256-bit frame buffer and the poster on Mobile01 claims that the 512MB version will be able to perform 40 Giga instructions per second compared to only 27 for the 8800 GTS 640MB.
However, this won't reflect the overall perfromance of the card, this only has to do with the stream processors.
More here in Chinese