No idea but, a DirectCompute miner could certainly be useful as low-end/mobile ATI GPUs don't support DirectCompute but not OpenCL.
cool. when bigger PCI-e switches appear in market, this can become really handy.
he said something about "obviously necessarily thing to write serious program" that AMD forgotten to introduce in OpenCL[but promised to add in 1.2 version], but support in DirectCompute 5 to make writing appz of virtually any kind simpler/elegant/faster.
as i get it its general purpose instruction/dataflow-related trick or something like it. referring "common sense".