The main limitation of RV735 was the 128-bit wide bus, but ATI has been working on a new version of the chip, simply codenamed RV740 that will end up with a 256-bit bus.
This card should be available in Q1 2009 and it looks that it slipped the original schedule to launch in late 2008. This card will help ATI has a better position and more power in under $100 market and put the Geforce 9600GT under even more pressure.
This is obviously a 55nm chip, and it will help ATI dominate the sub-$100 market and try to get as many OEM deals as it possibly can. We expect to see some products based on this chip in Q1 2009.