VR Zone informs us about some additional information on R600, RV610 and RV630:
ATi briefly mentioned to their partners a 2nd generation Unified Shader Structure and a new hardware Crossfire for R600 family which can be bridgeless yet faster. The retail card is half an inch longer at 9.5" and the OEM/SI version remains the same at 12". It comes with 512-bit memory bus and 1GB DDR4 at more than 2GHz frequency. Core clock remains a mystery as yet.
There will be 3 variants of RV630 supporting DDR2, DDR3 or DDR4. For low-end RV610, it will be built on 65nm process and there are 2 variants; RV610LE supporting DDR2 and RV610PRO supporting DDR3. Memory clock for RV610LE stood at 400Mhz while RV610PRO is at 700MHz.