TuioPad is an open source TUIO tracker for iOS devices such as the iPad, iPhone and iPod touch, which allows multi-touch remote control based on the TUIO protocol. This app is available free of charge and can be used in conjunction with any TUIO enabled client application. Its source code is also available under the terms of the GPL and therefore can be freely used for the creation of open source TUIO enabled mobile applications. Apart from that the TuioPad is also a useful tool for the development and testing of TUIO 1.1 client implementations.
You can find further information about the TUIO protocol and the various TUIO enabled application environments at the TUIO.org portal.