M-Audio and Frontier Design have partnered on a good idea: totally wireless MIDI keyboards. The first in their line are the MidAir 25 and MidAir 37
The new wireless protocol that has low enough latency for some audio applications.
The Midistream system uses UHF radio: "Simply put, we found the UHF band to be superior. We started out by developing both systems, but abandoned the Bluetooth system due to its high latency and other performance problems."
Being untethered will be liberating!