By Katie Marsal

Published: 06:40 PM EST

Apple on Monday evening released Mac OS X 10.5.4, the latest significant revision to Leopard and a key part of its online strategy. Also, Security Update 2008-004 and Safari 3.1.2 for Tiger address security issues for earlier Mac OS X versions.

The update (59MB for 10.5.3 users) is considered an important precursor to Mac support for MobileMe, Apple's imminent sync and hosting service.

In addition to laying the groundwork for the future replacement for .Mac, the update is also key to fixing a number of major bugs identified since the release of Mac OS X 10.5.3, including an Adobe CS3 corruption bug with remote file saves and a chronic shutdown flaw.

Also mended with the fix are reliability with AirPort when on 5GHz 802.11a and 802.11n networks, iCal stability, access to secure websites with Safari, and a number of fixes for Exposé and Spaces.

Support for additional cameras' RAW photo formats has also been expanded, the company says.

Apple recommends the update for all Leopard users to improve the stability of their systems, and rolls in previous security updates released between Mac OS X 10.5.3 and the new update.

Additionally, the company has released Security Update 2008-004 for Mac OS X Tiger client (Intel, PowerPC) and Tiger Server (Intel, PowerPC) that bring security fixes built into Mac OS X 10.5.4 to the earlier operating systems, including protection against vulnerabilities in significant components such as CoreTypes, the Dock, SMB File Server, Ruby and Webkit.

A third update, Safari 3.1.2 for Mac OS X Tiger, fixes a specific flaw in WebKit (addressed for Leopard in 10.5.4) that would allow malicious JavaScript to either crash Safari or else allow running hostile code through the browser.

The full list of fixes in Mac OS X 10.5.4 follows below:

General

• Includes recent Apple security updates.
  
• Resolves an issue with saving and reopening Adobe Creative Suite 3 files on a remote server.
  
• Includes additional RAW image support for several cameras.
  
• Addresses an issue that may result in a partially installed X11 application.
  
• Improves L2TP VPN client reliability.

AirPort

• Addresses AirPort reliability issues with 5GHz networks.
  
• Addresses AirPort issues that may result in slower performance in Logic Studio or MainStage.

iCal

• Improves overall iCal reliability for meeting requests, cancellation notices, delegation, and syncing with iPhone.
  
• Resolves an issue that prevents deleting an iCal event without notifying the creator.
  
• Addresses an issue in which events in all calendars affect availability. A checkbox now enables information-only calendars to be transparent from free/busy lookups.
  
• Resolves a UI issue preventing delegated calendars from showing up as a separate window.
  
• Addresses an issue with copying and pasting attendees from one event to another.
  
• Resolves an issue in which iCal may not delete events after a specified time interval, even when set to do so in iCal preferences.
  
• Addresses an issue in which To Dos cannot be marked private.

Safari

• Addresses a potential performance issue when loading secure web pages.
  
• Resolves issues that may be encountered when accessing secure web pages with client certificates that reside on a smart card.

Spaces and Exposé

• Addresses an issue in which switching from a space with a Finder window keeps the Finder as the active application instead of the application residing in the destination space.
  
• Fixes an issue in which dragging an application from the list of application assignments in Spaces System Preferences does not assign the application to the desired space.
  
• Resolves an Exposé issue that may result in only a subset of windows being shown.