c74 is an iPhone app that let’s you connect your device with Cycling ’74’s Max/MSP 5 and create custom layouts which can be operated directly from your iPhone. In order to connect to Max you will need to download the free external app at http://www.nr74.org/c74/c74.zip
(OSX Max 5 only)
Especially interesting is that custom interfaces are built straight from within Max, with presets stored etc and sent directly to the iPhone. You can also receive accelerometer data, GPS, compass, shake gesture and proximity data.
Communication between the app does not rely on OpenSoundControl but instead uses a straight forward communication socket, which offers a reliable connection.