Since kernel.org remains down, I've set up a man-pages git repo on github, at https://github.com/mkerrisk/man-pages. To clone the repo:
git clone firstname.lastname@example.org:mkerrisk/man-pages.git
I'm undecided yet, but this may become the permanent location of the upstream repository.
Update 2011-10-04: as a couple of people pointed out (and as I noted in some later posts), the better commands for cloning the repo would be:
git clone git://github.com/mkerrisk/man-pages.git
git clone https://github.com/mkerrisk/man-pages.git