It may be of interest to some on the list that we have open-sourced (BSD licenced) our core Gambit-C based development framework for producing cross-platform applications on Android, iOS, OS X, Linux, Windows and OpenBSD. The GUI is OpenGL based with a widget system written in Scheme. The framework can also be used for cross-platform console/embedded applications.
The source code, including examples, is here:
https://github.com/part-cw/lambdanative
A paper describing the framework and its use for various medical applications on smartphones and embedded devices will be presented at ICFP'13 in Boston in September.
Chris