They apparently had orders for 100,000 of the things.

I guarantee that had they not made a big thing about xmbc and video playback on it that they wouldn't have sold anywhere near that. I frequent some other forums which are non tech related and I was even surprised to see talk of the pi. Nobody mentioning development, just people excited about running xbmc.

As for getting the os on it, xmbc will have a single click tool for creating the sd card for it. Put sd card in, connect hdmi & power, job done.