Tokyo Inferno/Plan 9 Users Group - Offers free accounts on public Plan 9 servers, documentation (some in Japanese), mirrors of Plan 9 software, and other resources. - http://www.tip9ug.jp/en/index.html
IWP9 2006 - First International Workshop for Plan 9 and Inferno. - http://lsub.org/iwp9/
Plan 9: The Way the Future Was - Essay compares Plan 9 to Unix, parts of Plan 9 being implemented in Unix. From Eric S. Raymond's book The Art of Unix Programming. - http://www.faqs.org/docs/artu/plan9.html