A menu item for git-revert
was added recently to gitk:
commit f74455ab216bdc4f21a733f75ddd6974634c5df1
Merge: 8d97506 76bf6ff
Author: Junio C Hamano <gitster@pobox.com>
Date: Mon May 13 07:51:41 2013 -0700
[...]
gitk: Add menu item for reverting commits
Just clone the git sources from git://git.kernel.org/pub/scm/git/git.git