I recently installed Homebrew on OS X and observed that the Homebrew binary path was added to the end of $PATH instead of the beginning, so even though I installed Python with Homebrew, python still resolved to the OS X version. Instead of fixing this in my ~/.profile with prepending the Homebrew path to $PATH, I edited /etc/paths and moved the Homebrew path to the first line. Now $PATH always has the Homebrew path first. This is convenient for working in Terminal, but I have to cross my fingers that nothing in OS X breaks.