I smell the reek of fanboy that hasn't showered in at least several weeks.
The R600 WILL have 512-bit GDDR4 memory and it WILL have at least 1gb of VRAM. It's core clock speed will also be most likely 1ghz or more. These basic specs have been confirmed by many other sources than theinq. And AMD/ATI already has testing units.
The fact of the matter is, from the looks of it, the card will eat the G80 for breakfast. Although as already pointed out, we can't be sure about anything until there are actual benchmarks out.
LOL @ the comment of nvidia coming out with the "8900". The X900 (where X= 7 or 8) series cards that nvidia releases are just refreshes of the X800 cards. To bring the G80 up to spec of the current status of the R600, nvidia would pretty much have to release a 9800, which won't be happening for a while. I am not an ATI fanboy and I own all nvidia cards, but I just find it so annoying that 90% of the people here always dismiss ati and say "OMG TEH NVIDIA PWNZORZ T3H ATI11!!!!!!11!!!!11!!2"
Why not? Because you think nvidia is better than ATI?