Hello,
ipMIDI sends simple raw MIDI data over Multicast UDP. The protocol is not proprietary.
Example source code:
http://llg.cubic.org/tools/multimidicast/
ipMIDI OSX is freeware
79$ is the 3-client windows version.
I am not experienced with iphone/ipad development.
With Windows notebooks I had problems with the power saving modes of the WLAN NICs. If enabled you can expect a high latency.
Kind regards
Daniel Schmitt
nerds.de