Nvidia plans to launch two version of the Geforce 9600GT. The reference design has 512MB memory but some partners will launch a bit more expensive 1GB version.
Memory still plays an important role in consumers' minds and ATI and Nvidia are already selling Radeon 3850 1GB, as well as 8800GT with 1GB. Geforce 9600GT with 1GB doesn’t come as a big surprise, as the memory got cheaper, but unfortunately you cannot count on a huge performance increase with a 1GB card over the 512MB.
Nvidia uses DDR3 memory with 256-bit memory interface and it was time to move from the rather limiting 128-bit interface that was used for years.