In the Summer of 2005 I had the pleasure of participating in Google's Summer of Code program, that sponsored students to work on Open Source projects. I got accepted on a proposal to port Gaim (An open source instant messaging client, like Messenger) to the GPE ("GPE Palmtop Environment"), which is a linux-based environment for handhelds, like the HP iPaqs and Sharp Sauruses.
I succesfully ported Gaim, and it is now in widespread use by users of the GPE environment. The porting is done with a series of patches against Gaim 2.0.0-CVS, which is as yet not released. The patches can be found here. The prefered way of building GPE and its applications is to use the OpenEmbedded toolchain, which automates cross-compilation of almost everything needed.
In the future i hope to contribute more to the GPE project, to make it even more useful and cool :-)