The Haiku Operating System is the open source resurrection of BeOS, the Be Operating System. The project started in 2001 under the name OpenBeOS and changed it's name in 2004 to Haiku to circumvent any legal issues. The kernel is a fork of the NewOS kernel written by an ex-Be engineer. The Haiku team focussed on binary compatibity to BeOS 5 and started to replace single parts of the system with an open source alternative.
Haiku took part in the GSoC 2009 where five students/project were accepted. It is the second time that Haiku took part in a GSoC. One interesting and promising project is the port and integration of WebKit into a native browser for Haiku.
If you are interested in alternative (open source) operating systems or you were ever interested in BeOS or even a fan of it, then you should get Haiku and try it out yourself. You'll find the press release about R1/Alpha 1 here. Please keep in mind, that this is an alpha release, which means that it is not yet feature complete and is still under development and not a finished product with lot's of polishments/service packs/etc. It is unusual that a software is so stable in this state, but hey this is good for us, the users. And it's already pretty fast.
Long live Haiku, thanks to all the developers and thank you for licensing all your stuff under the terms of the MIT license! ■