There's a major new release of the FOSS project LinuxMCE that includes whole-house HD PVR, movie, music and photo server, integrated telephony and smarthome.
All a/v source devices, DVD jukeboxes, and online media are shared through the home so you can put all your a/v gear in a rack in one room,
with only thin clients in the rest of the rooms. It includes a gyro-controlled UI that lets you navigate long lists of media and the TV's EPG by
waving, like a Wii, for fast, smooth control. Also wave to scan through your media and adjust volume and lights.
There's high-def demo walkthrough on Google Video, see: linuxmce[dot]org. Installation is 25 minutes and every step is shown starting with a clean PC.

I watched the 24 minute demo on it and it's pretty nice. It definitely beats the pants off the old Plutohome option :) I've got an extra pc sitting here so I'll give it a go and see how it does with my components when I get a chance.

The STB integration that linuxMCE allows looks pretty cool. I like the idea of being able to seamlessly switch between the two, but unfortunately, control TV is not supported (according to the vid). It is the best integration of a Moto DVR and an HTPC I have seen.