Last December, when I was in Australia and started to work on the Object_Freezer code, I "dived into" Bazaar (bzr) and learned the value of local commits as they allow me to work offline, e.g. when disconnected during travel. Thanks to bzr-svn, I can now work offline for PHPUnit development as well.
He shares his setup - a local shared repository for branching/trunk work and a linked checkout of PHPUnit between Bazaar and Subversion. This allows him to commit locally with Bazaar and, when he gets back online, issue a "merge" command to make the push back out to Subversion's remote repository.