Way back in 2004, I used brickOS via Cygwin to build a LEGO robot capable of playing Connect4... the event was a competition by rtlToronto, jokingly called Deep Yellow. Amazingly, there are some pics still online here: http://www.brickshelf.com/cgi-bin/gallery.cgi?f=71985
Edit: snark aside, another user points out that LegOS is taken by a mindstorms operating system: https://news.ycombinator.com/item?id=21285290