That's a good question. Even NVIDIA seems reluctant to give a release date.
www.nvidia.com states that the GeForce 6800 Launch is during the end of May and well into June, so we can expect it pretty damn soon.
They need to get their asses in gear! ATI already has their Radeon X800 Pro out.
I'm still curious to see the Radeon X800 XT non-Platinum Edition and GeForce 6 6850 Ultra benchmarks. Neither one has been released to reviewers yet!
-Lasereth