Currently Fedora 13 should work.
To determine which version you are using, just run the following (you may need to install it first, see below for instructions):
A full build using sugar-jhbuild will require about 3 Gig of disk space.
yum install redhat-lsb
Other than that and the packages mentioned by
./sugar-jhbuild depscheck (please see the non-distro specific instructions) nothing else should be required.
If you notice that any package is required, but not mentioned by depscheck, please file a bug report (login required first, but currently no automatic redirection to login page) against the sugar-jhbuild Component on the Sugar Labs bug tracker.