We seem to find ourselves needing to switch out Eneloops for our Magic Trackpad at the least opportune times, and Mobee thinks it has the answer. Its new Power Bar is a USB-rechargeable cylindrical battery pack for the trackpad that claims to offer 10 days of use from a charge after taking 6 hours to fill up, and should be good for 500 charge cycles. Hopefully it has the option of providing tethered power to the trackpad too, though that's not mentioned on the company's product page.
Mobee has history with Apple accessories, previously releasing the Magic Numpad films and inductive Magic Charger stand for Apple's Magic Mouse. The product looks well-designed, barely adding any bulk to the trackpad while offering a solution to a problem we often have. We didn't get great results from the Magic Charger ourselves, though — it didn't hold a charge for very long, the power indicator in Mac OS X was unreliable, and it was a little difficult to get it to charge in the first place. That said, it was a more complicated product than the Power Bar seems to be, using inductive charging as opposed to a simple USB cable. In any case, we're filing this one under "wait and see" for now — it ships in March for $29.90. If you'd like to try Mobee's inductive charging for yourself, though, there's also the new Magic Feet, which ships the same month for $149.90 and provides power to the Magic Mouse and either the Magic Trackpad or Wireless Keyboard. See a picture of that below.