Yesterday Sony announced the release of the  MDR-RF4000K.These headphones use a secure digital RF signal -provides up to 100 feet, and their foldable design allows them to sit inside a slim storage case which also doubles as a charging cradle.It has a built-in NiMH battery is good for about 7 hours of continuous use on a single charge.
You can switch to using a single AAA,if the power dies out.The battery  is good for another 10 hours..thats pretty legit.