There has been R600 Gallium3D OpenCL support for running basic OpenCL demos and now the support has come to the RadeonSI driver, which supports the Radeon HD 7000 series and there's early Radeon HD 8000 series support.
Unfortunately, the OpenCL Gallium3D support still isn't really good for running more than just a few basic OpenCL demos and no performance-sensitive computationally-intense workloads that can be tossed at the proprietary GPU drivers. The open-source OpenCL driver support also isn't enabled by the default and the Radeon support requires using the R600 LLVM GPU back-end that isn't yet found in a released LLVM version.
The initial RadeonSI Compute support can be found with this Mesa patch in conjunction with using the latest R600 LLVM GPU back-end code.
While it's nothing too exciting at this point for end-users simply wanting to exploit OpenCL on their newer Radeon GPU, at least it's another step forward.