RussCox has ported a great deal of the PlanNineFromBellLabs functionality to *nix user space.

http://swtch.com/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.

It includes the RcShell, and many other commands and file servers.

For a list of available programs, libraries and services see the plan9port man pages: http://man.cat-v.org/p9p/

* supported systems:
** Linux (x86, PowerPC, and ARM),
** FreeBSD (x86),
** Mac OS X (x86 abd Power PC),
** NetBSD (x86 and PowerPC),
** OpenBSD (x86 and PowerPC),
** SunOS (Sparc)

See also 9base, a subset of the command line tools in p9p: http://tools.suckless.org/9base