Homebrew breaks with gcc out-of-date after Lion OSX install
Until all the kinks get worked out, you'll want to track 10.7 and Xcode 4.x issues at https://github.com/mxcl/homebrew/issues

In this case, be sure you actively manage your $PATH variable to keep your preferred versions of redundant apps first in the expansion.

Always hard coding full paths is tedious, but lack of it causes these bumps when new binaries show up in your path unexpectedly.