What happened with ATI 4850/4870 Computex introduction

I think that what has come out of it is that they have delayed the launch and as a knock on from that the NDA (non disclosure agreement) has been extended also. So they may have seen the card and know the specs, even written the reviews but they cant publish untill th eNDA has expired.
Mactronix

I have a feeling they showed alot of them, but in behind closed door scenarios, and locked under NDA like Mactronix mentions.

I suspect a very good reason to keep the information close to their chest is that if nV is just taping out their 55nm parts, no point in giving away the information before anyone can actually buy one, including tell nV what to target with that optical shrink and potential respin (although likely not at A0 silicon yet so not a respin per say so much as tape out again and avoid a respin).