"Rob, Ken, Dave, and I use Macs as our desktop machines, but we're a bit of an exception. Most Google engineers use Linux machines, and I know of quite a few ex-Bell Labs people who are happy to be using sam or acme on those machines."

http://swtch.com/plan9port/

http://swtch.com/9vx/

These give you some plan9 features on mainstream unix.