Long ago, Debian Plan9 could go nowhere because Plan 9 is not DFSG compatible*...but now there's 9front** and it's been gaining some steam. It's a fork of Plan 9 under the MIT license.
* http://lists.debian.org/debian-devel/2003/01/msg01811.html * http://code.google.com/p/plan9front/ So, who are the people that were planning the Debian Plan 9 port way back when? Where are they now? Is anybody else interested in picking this up?