They said the chips will be available tomorrow in large volumes, no specific numbers were shared but it will be in the 10,000s range with more volume to come soon.
Also interesting is the progress on 55nm, NVIDIA is aggressively moving to 55nm technology and says the GeForce 98xx and GTX 200 series will both be fully transitioned to 55nm by the end of the year. The NVIDIA guy didn't speak very clearly but he said something among the lines of "first 55nm G92 GPUs start shipping this quarter, with heavily transitioning of G92 and GT200 to 55nm next quarter".
What he means with this is a bit unclear though. In the best case scenario it could mean the 55nm G92 GPUs will be available before July but it could also be that he was talking about shipping the first samples to their partners and in that case it could take a while until the first cards end up in retail stores.