SnapStream have announced their next major rev will include support for HDTV recording and playback. This is pretty significant, as HDTV support in software PVR applications is still fairly new, with MythTV's HD playback in early stages. It sounds like Beyond TV will support at least four different HD tuner cards as well.
By all reports, Microsoft's Windows Media Center is holding off on support for (update: CableCARD, not OTA, which it already has) HDTV recording/playback until Longhorn is released next year,
so for those running windows-based home theater PCs, BeyondTV may be the only choice for quite a while. so hopefully software PVR applications are soon to follow.