PicoGUI is an Open Source project to create a new GUI architecture for embedded systems. It provides the same functionality that you would expect from an X server, a widget set, and a window manager. Instead of compatibility with existing software, PicoGUI is focusing on an innovative architecture especially well suited to handheld computers, PDAs, cellphones, and other embedded systems. It is client-server, but almost everything is implemented in the server including widgets and themes. The theme system and flexible video architecture allow it to run on a wide variety of displays, from large desktop monitors to text-only LCDs and everything inbetween.
The project has been underway for almost two years- it runs on several architectures including the TuxScreen, VTech Helio, Agenda VR3, Psion, uCsimm, and a few commercial products in development.