Besides Linux, BeOS was another operating system I fell in love quickly. OpenBeOS was the first open source project I joined way back. Unfortunately, I wasn't able to really contribute and it is still one of my hopes that I could.
OpenBeOS has come a long way and also it's called Haiku now.
I grabbed the anyboot installer from Haiku's site and immediately proceeded to install on a virtual machine. Oh, the glory days of distro hopping. I have not read the installation guide yet but setup is straightforward, one just have to initialize the hard drive manually.
The installer seemed to hang though on getting to the restart, but everything was running very nicely after a manual restart. It might have something to do with using plain qemu instead of kvm. Using kvm provided a very noticeable boost.
It is very impressive so far.
Finally, I was looking for the old newsletters but took some time to locate copies. They're a good read, the developers were also quite the visionaries on their own right.
OpenBeOS Newsletters: http://haikuware.com/directory/start-download/utilities/miscellaneous/my-haiku-newsletters