Matt Domsch occasionally rebuilds rawhide in mock, in order to catch packages that have bitrot that won't compile any longer. He just recently started mass filing bugs for them, and here's the status of those bugs.
Good, but not wonderful. Matt tries really hard to make Fedora a self-hosting distribution, so make sure to get those bugs fixed so the packages can compile!
NOTE - the links above, due to bugs in bugzilla's reporting interface, may lead to the desired list, or it could lead to all of the bugs :/