Saves replacing your batteries http://www.engadget.com/2011/04/12/mobees-magic-bar-brings-inductive-charging-to-your-apple-blueto/
Looks useful however I'd probably loose it between keyboard charges.
Looks an expensive way to solve a trivial problem. I use a wired keyboard, but for the Magic Mouse I just rotate two sets of rechargeable batteries... I'm not paying $50 to save a few moments work once a week(ish) :eek4:
I use eneloop rechargables, they last months on the keyboard and I rotate every three to four on the mouse, so I have a spare set on trickle charge ready, and that's with heavy usage.