if you want preview driver for C++ support in OpenCL then they are at AMD APP SDK download page http://developer.amd.com/sdks/AMDAPPSDK/downloads/Pages/default.aspx
AMD release preview drivers only for windows. for Linux it is released extraordinaly
The lack of the Linux one is really annoying. I just got a 7970 and there's a useless "Unsupported hardware" watermark in the corner with the current driver.