Related link: http://www.kurobox.com
So, it runs on a PowerPC processor, and already runs a working Linux environment. It has a thriving user community in the Japan as well as a starting-to-thrive US community. All you need to do is throw in a hard drive. This is probably the most hackable device since the Tivo for the amount of creative stuff you could potentially do with it.
All in all it looks really cool. Now all I have to do is figure out how to convince myself I need it for some project around the house :-)