Yes, it's been done a few times:

http://talk.maemo.org/showthread.php?p=726652
http://talk.maemo.org/showthread.php?t=72753

And a few others, just do a search for "inductive".

I particularly like the one that mods the battery rather than the phone. Not only you it leaves your phone intact, but it also allows you to charge the battery out of the phone. It actually gives me an idea. After a recent purchase I have quite a few batteries going spare