Apple has seeded a new version of Mac OS X Leopard (9A500n) to developers today.
The latest update arrived through Mac OS X's built in Software Update and reportedly improves stability and provides general fixes. It is recommended for all users running Mac OS X Leopard 9A499. Previous seeds have introduced visual tweaks. There have been no reports yet about any visual enhancements in the latest build.
Apple recently requested feedback on the previous build (9A499) to all developers. The final consumer release of Mac OS X Leopard is due in October.