OSDev.org

Any of you guys ever actually tried that OS?

http://cm.bell-labs.com/plan9/about.html

I know its been out for a while but the simple idea of being able to share ressources such as processes and the like over a file system (v9fs I believe) sounds very cool and somewhat hard to grasp.

Yes, I used it about an year ago (there was 4th edition then). Although its has some really good features(like namespaces) but not enough that it can replace its elder brother unix. The kernel is very simple(and portable too) and thus easy to understand. I'd suggest you look out for one of its derivatives called Inferno instead of Plan9. Inferno has, in my opinion, way much cooler features (like integrated Dis virtual machine).