Jose Vilches reported on this a few days ago, but I think as of his posting on October 27th it may not have been open to everyone.

I'm not sure when it happened, but I think anyone can now use it if you 'opt in', since it is still in beta.

I did it on my 1.83Ghz Core Duo Mac Mini hooked up to my 46" TV. Things went reasonably well. The video froze on the initial full screen attempt, audio kept going. On the 2nd attempt things worked fine though, and I watched a TV episode for ~42 minutes without any problems. It did use a ton of CPU power, but that isn't exactly a powerful cpu in the Mini, and just the integrated Intel video.