BOINC 6.x.x = CUDA/CAL/Brook+
BOINC 7.x.x = OpenCL support added
Prior to 7.x.x, some projects made OpenCL apps for AMD/ATI but since BOINC didn't support OpenCL, they just named them ATI apps so the BOINC scheduler would send work. That has caused some confusion because if a user is running BOINC 6.x.x and a recent Catalyst version, the project will send it work only to have it fail since the older GPUs (e.g. HD 3870) don't support OpenCL even if they have the latest drivers. Or, a user may have an older driver that doesn't include the OpenCL runtime and even though the GPU supports OpenCL, the app will fail due to the missing driver. In theory, that is all fixed with BOINC 7.x.x which reports whether each GPU supports both CAL and OpenCL as separate attributes.
AFAIK, The PG apps were OpenCL apps named as if they were ATI apps. I believe DiRT is the same. I don't know for sure about WCG but my guess is that the apps are OpenCL as well.