It's quite a nice looking device... sort of like the offspring of an iPod with an iriver H3x0, whose grandparents were flash-based devices. I think it would make a rather unique Rockbox device.
But like GodEater said, start gathering up some information and create a wiki page to post your findings on. Buy one of those devices as well, and experiment with it and see what you can find out about its filesystem, chipset, and whatever you can gather.