Funny, I was looking at something similar the other day at a compusa and was wondering if I could get Linux to talk to it. After reading your post I went sniffing around a little more. It looks like dozens of manufactors OEM the same equipment and brand it as their own, besides Oxyl there is another project called swisscenter ( newbielink:http://www.swisscenter.co.uk [nonactive] ) that provides a GPL interface via php that works on Linux and windows.
Unfortunately this box is really just for hardware decoding and output, it doesn't have much raw cpu or memory ( or disk at all ) for running an os, instead a PC streams the media, graphics and menu structure to it.
Now, I could see a very light weight orbiter (much like the web orbitor) + media streamer interface that could talk back to pluto, this would be great as the Buffalo OEM version is $100 bucks on the BestBuy website and has a built in DVD player, components out and supports MPEG-2, WMV, AVI (MPEG-4), MP3, LPCM, JPEG, BMP, PNG and GIF for streaming, and if a DVD VOD is unencrypted is will support DVD menus as well ( i think).
I wonder why I have not heard more about this, I might pick one up to run swisscenter as is!