I haven't seen it get used very often, but during SJ keynotes, they have been using this. When I watched, it delivered really high quality video, and managed to stay way smoother than any flash stream I've ever seen under presumably heavy load.

Granted, Apple probably throws a lot of hardware at those events in order to make the tech. look good. So, not an objective appraisal by any means, but it's worked well for me.