When it released its first GeForce 8800-series graphics cards back in 2006, Nvidia outfitted the products with unusual amounts of memory. The 8800 GTX had 768MB, the 8800 GTS came with 640MB, and Nvidia later followed up with a cheaper 8800 GTS with 320MB of RAM. That trend pretty much stopped with the advent of newer 8800- and 9800-series cards, but according to a report by Fudzilla, it's set for a comeback in Nvidia's next-gen products.
Fudzilla says Nvidia has two next-generation graphics cards up its sleeve. One is code-named D10U-30 and will feature 1024MB of GDDR3 memory, while the other is code-named D10U-20 and will supposedly come with 896MB of GDDR3 RAM. If accurate, this information suggests Nvidia could differentiate the two models by playing with the width of the memory bus. Fudzilla doesn't quote any numbers there, but the D10U-30 could have a 512-bit bus, while the D10U-20 could conceivably feature a tighter 448-bit bus.
We may find out for sure soon. The rumor mill suggests Nvidia's next-gen cards are due out in the third quarter of this year, possibly as early as July. A more recent report by Expreview also suggests the newly launched GeForce 9800 GX2 may reach "end-of-life" status in June in order to make way for the new GPUs.