One of the beauties of open source software is that any programmer can take its existing source code and add to it - or "branch" it off in exciting new directions. Eugene Antimirov recently reported in his blog that he has created a version of Labyrinth (an open source mind mapping app written in Python) that is adapted for the Nokia N800, a clamshell style cell phone/PDA, utilizing its Maemo open source operating system. He reports that it's still in "alpha" stage (not ready for prime time, probably still a bit buggy).
For more information about Labyrinth, please visit its web page.
Thanks to Kevin Tofel from the jkOnTheRun blog for uncovering this little gem.