A new version of OpenElec is out - it's reckoned to be the best build of XMBC for the Pi (very stable and lightweight). The two reasons I'd like to use the Pi (well, aside from it being a cheap AirPlay replacement) is that it can playback my MPEG2 off-air recordings and be a very competent BBC iPlayer.
Licenseing for MPEG2 playback - it's a very modest couple of quid to enable hardware MPEG2 decoding (MPEG4 and H.264 is there already);
the root p/w for it is openelec
With that done it's trivial to grab the iPlayer app and install it - so far it's played very nicely!
The other VOD apps you might like are;
- Blip.tv (feat. The Engineer's Bench podcast!)