Yeah, it claims to do mkv, so hdtv stuff that is x264 in the mkv container should play in its full hd glory. Same with movies.
Right now I'm converting x264 with mkv2vob app for the ps3 but that is only in the bedroom. The 360 is in the main room, and there's no speedy way to convert for it. I'm thinking this would be handy in the main room for stuff like that.
I'm getting quite pissed off with my crappy cox dvr, if I had something like this, I wouldn't need to rely on it as much.