Homebrew seems to be the hot new package manager for OS X, so while setting up a new system last night, I figured I’d see how it handled installing all the external libraries required for GeoDjango. The answer I quickly found out was, “extremely well.” Here are the steps:
$ brew update # make sure all your formulae are up to date
$ brew install postgis # this will handle installing postgres, geos, proj4, and postgis
$ brew install gdal