Apple Releases Mac OS X 10.5.4
Apple has released Mac OS X 10.5.4 Update for installation via Software Update
The 10.5.4 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/HT1994.
For detailed information on security updates, please visit this website: http://support.apple.com/kb/HT1222.
According to MobileMe's Terms of Service, Mac OS X 10.5.4 is required to use MobileMe services.