Meaning that the R600 is an obsolete product and ongoing development is occurring only on current-generation hardware, so no one is likely to try, even if it is possible to code around the R600's limitations (and it probably isn't, but I don't know). AMD has never made any mention of R600-based products in its OpenCL presentations, and when the manufacturer ignores an old product, everyone else tends to as well.Meaning that someone 'could' work on R600 compatibility? If so this work would be a driver update perhaps by either ATI / Apple or both?
I don't know enough about ATI's products to know for sure, but I do know that the R600 has substantially different programmable shader hardware than the R700 and GeForce 8/9, and that may well disqualify them from ever being OpenCL-compatible.
Sorry if I got your hopes up--I was trying to do the opposite!