to avoid the need to build the initial ghc package by hand in the buildsystem, I propose to make a seed source rpm including the upstream binary tarballs for Linux i386, ppc and x86_64 as a seed for Extras.
Ok here it is:
http://people.redhat.com/petersen/extras/ghc-6.4-1.src.rpm (67MB) http://people.redhat.com/petersen/extras/ghc.spec
-Jens