A kind reader updated my Objective-C export script for Blender to work with the 2.5 beta 6 version of Blender. You can find the new version on GitHub.
On a related note, if you make a change to your clone of any of my public repositories on Github, you can send me a pull request. I'm happy to take additions, bug fixes, and other updates back into the master repository.
Thanks to John Becker for updating the script!