I've now had the Mobee induction charger for a few days and wanted to share my thoughts with you all. I got this because by MM was eating batteries like crazy. Although inserting the replacement battery cartridge wasn't as easy as it looks, after a few minutes of fiddling, it finally snapped into place and is just a hair short of being completely flush with the housing. This is not a problem and I found no difference in the feel. The induction charger plugs into a USB port and will remain active while the computer is in sleep mode. It utilizes NiMH batteries which have a lower voltage then alkaline so when fully charged OS X shows a 65-75% charge level. Mouse can sit in any position on the charger and there is an indicator light to tell you it's charging or fully charged. So far after a few days it's been great. Use without charging wears similar to alkaline; recharging seems relatively reasonable (although I can't give exact time since I put my baby on sleep and went down for dinner. When I returned, MM was fully charged) I'm pretty happy with this product since I won't be scrounging for batteries anytime soon. 
(PS excuse quality of pictures. I used my blackberry)