Some fresh rumors regarding ATI/AMD's upcoming R600 have hit the web. According to this post on VR-Zone, R600 A15 silicon can hit 1GHz, but cards are going to launch with A12 silicon at somewhat lower frequencies.
It seems like ATi has successfully taped out a A15 silicon that is able to work at 1GHz probably we can hope to see another series of R600 cards with higher working clocks in the near future. The article suggests ATi's next generation R680 is scheduled for Q3 launch but suggested that NVIDIA will have G81 and the next gen. GPU ready to compete. According to our sources but still a rumor revealed R600 as X2800 series. There are 2 variants for XTX; 1GB and 512MB. X2800XTX runs at 750MHz core, 2.2GHz memory, 512-bit memory interface and GDDR4 while XT runs at 600MHz core, 1.8GHz memory, 512-bit memory interface and GDDR3.
No mention of the GPU's configurations yet, and the source is a post in their forum that references a Chinese website. As is the case with all rumors, take this info with a very large grain of salt.