Wireless USB? Why not use wifi? There are now plenty portable nas units, and battery operated nas units.
Anything the size of a flash drive would only give an hour or two of power anyway, and if you want inductive charging, use that with a wifi nas.
Wifi also should have much better range than any conceivable wireless USB or UWB product.
What does using USB gain over wifi?
Full Disclosure: I like keyless entry on my car, thunderbolt, wireless tech (adopted it back when it was from proxim) and have an ocz throttle that I love dearly (enough iops to boot off of and not tear your hair out)