Fudzilla: "Die shrink with minor changes"
"ATI said a few things about its new upcoming RV770 chips, and as we've said before you can expect RV770PRO with DDR3, RV770XT with DDR5 support and the top end, R700 aka (RV770X2) with two RV770XT chips in a dual-card configuration.
The new GPUs are 55nm and they are actually an architecture shrink chip with minor architectural changes. Of course, just as RV670, they do support DirectX 10.1 and at the same time, they will bring some significant performance improvements compared to the previous RV670 generation.
The new RV770 chip will also have great improvements in power consumption. The launch date is late Q2 2008, most likely June, but real volume availability is expected in early Q3 2008, probably July.
We still don't know the clocks or the official name."