What version of GHC do you use at Microsoft? Do you have a last-not-broken version which you use for developing GHC or what? If there is a last-not-broken version it would be good to have access to it.
We generally have 'ghc' pointing to the latest stable release (i.e. now it points to 5.04), and I usually install a snapshot whenever we make one. We don't develop day-to-day using snapshots, because switching over existing builds is a little annoying.
For quite a long time I ran an automated system which compiled GHC every night from CVS (using the previous version) and installed it on our system if the compile completed. This actually worked quite well, though I stopped doing it because the compilation system got more complicated, I had problems doing it on Sparc/Solaris, and it was too much trouble. If the compile finished it was unusual for the compiler itself to be hopelessly broken; to be on the safe side you could check it was able to compile Happy and Haddock. Something like this might be good. Of course it would have to be made very clear that such snapshot releases were for evaluation only, and that only the official releases were to be relied on.
Our nightly builds run a 3-stage bootstrap and then the whole test suite, so you usually have a pretty good idea by the end whether the compiler is a good 'un or not. You can checkout the scripts we use for the nightly builds from CVS: just 'cvs co nightly'. Setting up your own build using these scripts is fairly painless; Malcolm Wallace did it recently for Sparc to bolster our Sparc support a bit. Cheers, Simon