Happily, we've got a direct contact with the apple folks working on llvm / clang via  a friend of mine, and thus in turn Tom and some others. The most important piece is making sure the Clang patches land in Xcode 5's version of Clang (which is apple's variant that isn't strictly tied to a point release), because thats going to be the only C compiler for OS X by default very soon. 

So in some respects, because BSD/Linux distros provide system package managers by default, its easy for a user on those platforms to have a suitable GCC installed, less so with vanilla OS X, so the most important part is making sure that these patches land in the Clang that lives in Xcode 5. If it lands in mainline clang point release too,  great!  (ghc not being able to useable on macs without the end user needing to build their own ghc or figure out installing and switching to an older xcode would be a HUGE headache for the haskell community)

point being: exciting things! (and many many hearty thanks to Austin for the work to make this move along)

-Carter