The Raspberry Pi board ran a 1080p video (H264) over HDMI for eight hours straight, and the board was still cool to the touch. Playback shows no hiccups, which is pretty impressive considering the price of this board. Furthermore, the HDMI port on the Raspberry Pi is a full implementation - so it carries audio signals as well (although audio was turned off for the demo since it took place on a trade show floor).
The Quake III demo was interesting and all, but this? Heck, this only further cements my desire to get a few of these. At this price, they could be excellent extremely small media centers, or even a tiny server. Sadly, little information is available at this point about which media player the team was using; they say it's a custom one, but I would personally want to see it running, I don't know, MPlayer or something. Of course, I'd love to see it run Boxee (my media centre of choice) even more, but alas, I will have to find that out for myself once the board becomes available.
I want one of these today rather than tomorrow!