Check this video of TouchOSC acting as a MIDI controller over WiFi MIDI. He has set up a 16 pad (MPC style) controller with Record and transport controls to navigate the sequencer. Also uses a slider to control velocity sensitivity, which is a great solution for a multi-touch surface, but does alter the experience from the traditional tactile approach. He also notes near the end of the video that is has some small latency, but hardly noticeable.
I could definitely imagine using this in my studio and on stage without the need to bring or set up every controller I own.
I also like the simple UI that TouchOSC has provided. The UI serves the user with enough visaul indications and treatments to accomplish the tasks without limiting or distracting the user with detailed visuals and/or metaphors that could be outdated easily.
The possibilities…