GNU/Hurd is the name of the GNU operating system when TheHurd is used as the kernel.
Currently, TheHurd is not in a production-ready state yet, but you can still install it, if you just work a bit and already got linux working. You have to use Grub to boot (LILO doesn't support "Mach"), which is a good thing anyway.
You can follow also the instructions about Hurd on QEMU: http://darnassus.sceen.net/~hurd-web/hurd/running/qemu/
What the name "Hurd" means
According to Thomas Bushnell, BSG, the primary architect of the Hurd, "Hurd' stands for 'Hird of Unix-Replacing Daemons'. And, then, 'Hird' stands for 'Hurd of Interfaces Representing Depth'. We have here, to my knowledge, the first software to be named by a pair of mutually recursive acronyms." (from the GNU Hurd webpage)
Savannah Hurd page: http://savannah.gnu.org/projects/hurd
OSF Mach docs (manpage format): http://www.grawk.net/~nick/docs/cmu-mach-man.tar.gz
Code browser (in progress): http://teleport.medri.hr/~docelic/hxr/http/search