Apple is expected to release an updated Magic Mouse and Magic Trackpad anytime soon, this has been rumoured for a few months back that Apple is planning on introducing new versions of the Magic Mouse and Magic Trackpad. This rumour comes from some code in the latest OS X 10.11.1 beta which highlight model names for the potential refreshes for the accessories, Magic Mouse 2 and Magic Trackpad 2 as well as a new Magic Keyboard. The existing models currently use AA batteries and Apple also sells a battery charger which is included with 6 batteries. The new mouse, trackpad and keyboard may width replaceable batteries and opt for a integrated battery solution that may charge with lighting, much like the new remote for the new Apple TV.
Also the Magic Keyboard, Magic Mouse 2 and Magic Trackpad 2 may have Bluetooth 4.2.