Point to correct gist.

README.md

@@ -7,7 +7,7 @@ Quick Install to /usr/local
 ---------------------------
 [This script][gist] will prompt for confirmation before it does anything:
 
-    ruby -e "$(curl -fsS http://gist.github.com/raw/436471/install_homebrew.rb)"
+    ruby -e "$(curl -fsS http://gist.github.com/raw/323731/install_homebrew.rb)"
 
 Afterwards, [install Xcode][xcode].