Apple releases Mac OS X 10.5.6 update along with Security Update 2008-008 for Mac OS X 10.4.11 on Monday morning.

The 10.5.6 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.

For detailed information on this update, please visit this website: http://support.apple.com/kb/HT3194.
For detailed information on security updates, please visit this website: http://support.apple.com/kb/HT1222.

The updates can be obtained through Software Updates or Apple Support Downloads page.