Moving to Fedora Core 5 requires to rebuild all arch specific Fedora Extras packages. Accordingly build dates, this does not seem to have happened for this package. Please rebuild the package as soon as possible. When you did this already, ignore and close this bugreport please. For more information see http://www.fedoraproject.org/wiki/Extras/FC5Status.
Unfortunately I have had problems rebuilding ghc with FC5 on x86_64. IIRC it fails at stage2 linking: http://buildsys.fedoraproject.org/build-status/job.psp?uid=5713 (the log is no longer there). Even rebuilding with gcc32 didn't seem to help though - so I'm a little lost.
The end of the failing buildlog is bug 181024#c1 though.
This patch http://haskell.org/~gentoo/gentoo-haskell/portage/dev-lang/ghc/files/ghc-6.4.1-gcc41.patch is supposed to fix the issue. :)
More details in http://www.haskell.org//pipermail/glasgow-haskell-users/2006-March/009887.html
The patch worked. :)