Plan 9 from User Space (aka plan9port).

Plan 9 from User Space (aka plan9port) is a port of many Plan 9 programs 
from their native Plan 9 environment to Unix-like operating systems.

Notes:
MD5SUM/VERSION:
The tarball is recreated from the sources whenever a change to the tree
occurs. You'll find the current tarball at:
http://code.google.com/p/plan9port/downloads/list

Updating:
You can use Mercurial to update plan9port, read
http://9fans.net/archive/2009/12/108
http://swtch.com/plan9port/man/man1/hg.html