Developers no longer have to download all of XCode just to install the Apple version of GCC. This installer should work with Homebrew, although I believe you will see warnings when you brew install packages for now.
I already installed XCode 4.1 on one of my machines, but when I upgrade the other to 10.7, I plan on trying this out.
Install on top of Mac OS X 10.7 and Xcode 4.2.