How do I install GCC via Homebrew?

I am using Homebrew exclusively (i.e. I don’t, and won’t, use MacPorts or Fink). I also want to keep manual installations to a bare minimum.1 … But how can I install GCC? First of all, I’ve of course installed Xcode but the current version doesn’t ship with a decently up to date GCC (I need ata least 4.5, but would prefer the most recent one) – in fact, it doesn’t ship with a proper GCC at all (it

[linoleuml]

brew tap homebrew/versions