When he wrote this previous post on __autoloading classes, he didn't know he'd get as large of a response as he did. So, based on that, he decided to post a follow-up with a new version and some improvements.
The enhancements include: the addition of directory scanning for the files, using the SPL RecursiveDirectoryIterator for scanning, and Windows support (via the DIRECTORY_SEPARATOR constant).
The post also includes a note on the backwards compatibility (fine except for an issues with a preg_match_all) and a quick example of how to use it.