On the topic of OS's nearing release, Haiku is set for an alpha release in Sep[1]: http://www.osnews.com/story/22001/Haiku_Schedules_First_Alpha_Release_for_September_9

If you haven't heard of <a href="http://www.haiku-os.org/">Haiku </a>its a rewrite of BeOS from scratch. The aim of the first release is compatibility with the last official release of BeOS: R5. They're a good way down that path. As far as I know many apps that were built for R5 will run on Haiku. I've been following the project for a while now. Back in uni I downloaded an installed BeOS on my PC, this was obviously before the company went out of business/was bought by Palm (I think). The bit that interests me about it is that its GUI out of the box, much like OS X and Windows. Its attributes such as compactness, GUI, open source and POSIX core makes it a great candidate for high level embedded type projects I think. Things like the digital photo frame project I've had in mind for a while. Its one drawback in my mind is that the platform's primary language is C++, which I'm not a huge fan of. However if you're into C++ it might be worth checking out. If I recall correctly large parts of the kernel are written in C++ too.