Some time ago I’ve written a post-commit hook for Subversion in PHP, to make it easier to track code changes via email.
Because I based it on another hook, written in Ruby. Because it had no license attached to it, and because I had to rewrite it myself, I decided to license it under the new BSD license.
You can find the hook here: commit-email-color.phps.
Update 2008-06-13: added an option to disable colorcode the diffs.
Update 2009-06-17: fixed a bug: now displays the full commit message instead of just the first line.