I had thought of that as well. Let's refine this idea a bit:

Maemo-powered touchscreen devices on the back of every seat. Has a SD slot that you could bring your own music/videos along for the flight. Don't like the airplane's selection of entertainment - well bring your own, and use it on a 12" media player on the back of your seat. Product placement! If done right (read, amazing hardware and software) - people would flock to get similar devices at home. There are issues - requirement for airplane messages to override the IFE, etc.... some thoughts to mull in your brain anyways.