SBJ: CPU or GPU Volume rendering

I'm looking for the collective opinion about feasibility of
implementation of high quality interactive "volume rendering" on CPU
or GPU. Interactive quality of all publicly available VR options are
very far away from the best static VR images I can find on Internet.
There is a substantial time-lag between the newest hardware
capabilities and "software" brains inside; to minimize the risk of
wrong investments I'm looking for the "opinion-trend" among people
involved in rendering core development.

Thanks,
Stefan