There are a few models but you may not have heard of them as they are not the names you expect to find.
Snazio, Buffalo, Kiss and Zensonic are the ones I'm aware of.
Some of these can be had as purely streaming machines (they have no actual disc drive and will take HD content by wi-fi from your PC).
You'll find people talking about them here.
Zensonic was the one I was thinking of going for but there are no official importers (= no official support if there are any problems) in the UK.
You'll also find that each brand has people very happy and some tearing their hair out.
Personally I gave up on the idea
(I really do not want wi-fi *anything* in my home)
and so I went for what I reckon is the best price/spec balance of the last of the old tech and went for a Pioneer DV696 (which at long last Amazon are about to deliver.....I can see it on the tracker!) and long cables to connect my PC to my HD TV via component and surround set-up via 5.1 analogue connections.
It works great and I've saved a fortune.
The cost differential doing anything else is just not worth it right now IMO.
In 2 or 3 yrs when they've settled the pathetic and dreary little format war they're indulging in and the pricing of HD DVD is more sane (and mainstream players will also support Divx HD and Xvid HD) I'll come back to the market again and see what's out there.
Just my 2 pennies but I suspect I'm not alone in this attitude (and that's amongst someone interested in this stuff, the uncaring general public are probably even more turned off of the whole thing, not the best start for a new tech or what? )