Looking at the ATI web site and supported OpenCL graphic card, I discovered that any Radeon 4xxxx is marked as “Beta support” for OpenCL: it’s terribly bad to not support the mainstream cards found in the last 2 years on PC (or actual iMac on Windows!).
If you look at nVidia support for OpenCL (& CUDA), every GPU created since 2006 (GeForce 8800 GTS using G80 core) is compatible and fully supported!
Please, ATI, go ahead and ensure full support of OpenCL on these Radeon 4xxx w/ RV700 core (not asking for impossible support of older GPU), don’t let nVidia rule the GPGPU market!