Apple has released Mac OS X 10.5.3, the third major update to Leopard that brings dozens of fixes to the operating system, many of which are quite minor. The biggest changes in the 420MB upgrade involve reliability of Time Machine backups and Spaces, along with a handful of corrected issues in Mail. No specific security fixes are mentioned on Apple's list of changes, but the company does say 10.5.3 "includes general operating system fixes that enhance the stability, compatibility and security of your Mac." The update is available now from Apple's download site or through Leopard's built in Software Update feature.