When I ran git gui, I got this:
git gui
$ git gui git: \'gui\' is not a git command. See \'git --help\'. Did you mean one of these? grep init p
Adding to the path worked for me.
I just added this line to my ~/.profile and git gui is alive once again. &(%ing mountain lion. export PATH=PATH:/usr/local/git/libexec/git-core