Plan9 is an operating system that is designed to make up for all the mistakes that UNIX made. And it’s quite different from any of the current UNIX clones, be it any of the BSDs or Linux. To ease the migration, there’s a project called Plan9Port; which is essentially a port of several Plan9 utilities to the POSIX platform.
I recently made an ebuild for Plan9Port, also called Plan from User Space. Just ‘emerge plan9port’ and spread the Plan9 love!