I have not yet tried this yet, but I just downloaded the manual for the MainConcept MPEG Pro HD plug-in for Premiere Pro and it includes export to H.264 with presets for both Blu-Ray and HD-DVD. I just purchased the plug-in a few days ago and don't love the way it works, but I was able to import and playback XDCAM HD clips with it. Playback functionality is not quite as good as Vegas 7.0 but timeline scrubbing seems excellent and it even works well with my Bella jog/shuttle device. I burned a 720P HDV file to a BD disc a while ago and it was beautiful, but I was only able to attempt playback on the burner drive, not a standalone player. But now I find that my new MainConcept plug-in will export to H.264 which I understand is the best encoding scheme for Blu-Ray and HD-DVD, although seldom used yet for commercial discs.
I find this very intriguing and will post some feedback when I get to my home studio and have a chance to export and burn something in this format. I am extremely curious if something thus encoded will play on a stand-alone BD player such as the Samsung, which I understand that MPEG2 disc from a burner drive will not as of yet.
Too bad that nobody is selling an HD-DVD burner now because I have my own Toshiba HD-DVD player at home and could give it a try there. Now I'll have to find a Best Buy or somewhere that will let me pop in a disc and see if it loads. Of course, from what I hear, the disc may not only NOT LOAD but also refuse to come out! It'll be fun to explain that to the salesman.