Apple's Mac OS X 10.5 'Leopard' users should download the latest update to their OS, version 10.5.3 as soon as they can. The latest update includes a long list of updates (addressing no less than 35 security issues). Apple patching OS X 10.4 "Tiger" as well.

Some of the high-level fixes in 10.5.3 include updated Flash player, Apache Web server, CUPS (printer server), iCal calendar, Ruby, single sign-on and Wiki Server components.

There are also a pair of critical fixes for OS X kernel that could potentially have allowed an attacker to trigger an unintended system shutdown.

On the stability side and compatibility side, Apple has detailed a long list of enhancements for 10.5.3. On the general side of things there are fixes such as:

• Fixes a font issue that could result in Helvetica Narrow being used in applications instead of Helvetica.
• Addresses an issue with stuttering video and audio playback in certain USB devices.
• Resolves stability issues with Word of the Day, iTunes Artwork, and Slideshow screen savers.
• Fixes an issue in which certain attached hard drives may not show up in the Finder.

There are also stability and compatibility fixes for address book, AirPort (Wi-Fi), iCal, iChat, Mail, Parental Controls, TimeMachine and VoiceOver.

All told it's a lot of "stuff" that Apple is including in its latest update. 10.5.3 is the first major update from Apple since 10.5.2 came out in February of this year.