There's no reason, except in terms of software development, that a current STB manufacturer couldn't come out with an HDTV PVR *now*. It would certainly be expensive, since it would be a combination STV/PVR and would have to use a large hard disk, but it's something that should have been out by now. Even a PVR with 160GB would be great for plain ole timeshifting of HD - though it wouldn't take the place of a high-capacity NTSC unit for people who like to archive - since that would be about 17 hours. Given the paucity of options for recording HDTV, a unit like this would sell like crazy.
I think there are two reasons why nobody has come out with one yet: First, is the lawsuit/standards problem, which I consider one and the same. HDCP/MPAA versus the consumers^B^B^B^B^B^B^B^Bpirates. Things are STILL in flux (some upcoming models, even with DVI, are still possibly not in compliance with HDCP) and few are certain how things are going to shake out, particularly in terms of what will have the copy protection bit set and what won't - will an HDTV PVR even *function* for most programming?
Second, it's possible that some companies are waiting out their partnership agreements with Replay and Tivo, which I am certain included verbiage restricting them from marketing their own PVR products while the agreements are in effect. Panasonic and Sony, in particular, would be in a good position - given no legal contraints - since they have done Replay/Tivo AND produce set-top boxes. Going along with this theory is that the DirecTV/Dish merger is *still* up in the air, and a combination unit would likely include satellite capability as well.
In short, my [under-educated and under-informed] prediction is that we will see HD-capable PVRs in some form sometime middle to late next year. They will probably start out with 10-20 hours of recording and ramp up according to how far hard drives get by that time.
-Aaron
