I've been involved with Haiku since the early days, when it was still called OpenBeOS. I was team lead of the print kit at the time, and build meister (I setup the basic repository structure and Jam-based build system.
Since then I've become a little less involved, and others have continued the things I started as well. Today, Haiku is close to becoming self-hosted and is starting to look like a real usable alternative. Ofcourse, there's still lots to do, so if you feel up to it, check it out, and join the fun ;)