Well, it looks like Nvidia won't be releasing anything new this year. Like they've been doing for the past while, they'll just be tweaking their current line up to fight off ATis renewed threat. Their only plan for this year is apparently making their dual PCB GTX295 GPU into single PCB.
And it looks like ATi 4890 is going to do well. It's highly overclockable from what I've read. Won't beat GTX285 and 295 obviously, but the price/performance ratio is looking mighty fantastic...from the leaked benches.
More ATI 4890 benchmarks - The Inquirer
I don't know how many of you trust the Inquirer...but the leaked benches were pulled from other sites and they're the only ones I could find