I installed this stuff recently, after playing with Inferno for a while. I couldn't get Plan 9 to boot on real hardware or in qemu until a couple of years ago, but once I got up and running, the documentation was a little less than satisfactory (there are man pages and research papers, but not many "getting started with X" or "how to do Y"; maybe I've been spoiled by Linux, where howto's have been prolific for 15 years).

acme is really cool, even moreso now that there is Linux kernel support for 9P2000, so you can mount acme's filesystem and write programs in any language that does I/O to do arbitrary things to windows and text. rc is also the nicest shell I've ever used.

Plan 9 has always been a research OS (although I wonder if, had it been opened up at the right time instead of staying at Bell Labs, we might all be using it now). But the ideas in it are gradually making their way to the rest of us, which is what I'm really excited about. Things like the aforementioned 9P2000 support in Linux, libixp, wmii's use of 9P for scripting, and even Inferno are pretty nice. (Can you imagine if all of those horrid, monolithic GTK/Qt /Cocoa apps were as scriptable as acme is? Even the ones that give you a scriping language pale in comparison.)

Although I don't really use Plan 9, having the ports around has been great for showing to people what I get so excited about (although that's just a fraction), and the 9fans mailing list is possibly the best one I'm subscribed to. You hear more on that list about interesting software architecture and UI design than I thought possible. It's a great place to lurk.