I want an HDTV PVR as unencumbered as possible. Ideally, it would sit by the TV/cable box and communicate closely with my Linux computer. Failing that, it could be a card in my Linux computer, and I'd just have to snake a cable from the living room to the computer room. Unfortunately, this is a much more complex matter than I would have thought.
The set-back to the broadcast flag leads me to think I have more time to buy/build the right device, especially since it's unlikely to be reversed this year, but I still don't see any coming solution to the basic technical problems.
The main resource I've checked out is the EFF's HDTV-PVR Cookbook. It makes it clear that the only real option for me is limited to "terrestrial broadcast (free over-the-air) digital television using an antenna." Cable apparently uses encryption. Problem is that almost everything I'm interested in watching in HD is on a cable channel.
I suppose the fact that Tivo seems to be increasingly terrorized by big media and scorned by cable and satellite outfits renders unlikely our ever seeing an HD Tivo that allows capture to a Linux box.