There are currently two technical issues that require rebuilding of
packages.
1) a bad binutils was used in buildroots for almost two months that
caused all ppc32 binaries to need execmem. SELinux rightfully denies
this. We need to rebuild the effected packages so that ppc and SELinux
work again.
2) build-id (http://fedoraproject.org/wiki/Releases/FeatureBuildId)
Any binary package with a debuginfo package that hasn't been built
after the good build-id stuff landed needs to be rebuilt so that it has
a build-id.
The unique combination of these two has led to a list of 2845 packages
that will need to be rebuilt.
(http://jkeating.fedorapeople.org/really-need-to-rebuild) That's 598
packages that need rebuilding for the ppc32 issue, and 2831 that need
building due to the build-id issue (there is obviously some crossover).