Nvidia has canned NV48: No point making 20 MHz faster card
 

Nvidia decided to cancel its NV48 project and reliable sources are claiming that you won't see those cards at all. According to the original plan we were supposed to see those cards in Q1 2005 but Nvidia realised that it made no sense at all to push a 20 to 30 MHz faster card.

http://www.theinquirer.net/?article=19992