Get ready to to fire up Software Update, Apple has released 10.5.8.

What Apple tells us about 10.5.8:

The 10.5.8 Update is recommended for all users running Mac OS X Leopard and includes general operating system fixes that enhance the stability, compatibility and security of your Mac, as well as specific fixes for:

-compatibility and reliability issues when joining AirPort networks

-an issue that could cause some monitor resolutions to no longer appear in Displays System Preferences.

-issues that may affect Bluetooth reliability.

Here is more detailed information.