I had the same problem building on Linux. I found this on a wiki somewhere (can only find it in google cache now):

"""(Note: Make sure that if you build with gfortran that g77 is not installed on your system (or at least is not in your PATH when numpy is being built) as you need to link with the same compiler that you built lapack with when numpy builds. It will try and find g77 first which will lead to linking errors if you have built lapack with gfortran)."""

The trick for me was that step of removing g77 (or taking it out of the path) - then distutils seems to pick up gfortran fine, but otherwise it doesn't seem to work (even with --fcompiler=gnu95 etc)

Cheers

Robin