The patch is available from both Apple's support website and through the OS' own Software Update mechanism. The update is available for both the client and server versions of the OS, and separate update downloads target Mac OS X 10.4.2 and other, older versions of the software.

The combination updates for users of Mac OS X versions 10.4.0 and 10.4.1 are here (client) and here (server). The number of changes made to the OS is said to be significant, and you can find a comprehensive listing of the tweaks here. The fixes focus on Finder, Mac OS X's Spotlight search system, Mail, the Safari web browser, .Mac and device synchronisation, networking (including AFP, SMB/CIFS, NFS and FTP network and file services, plus AirPort and Bluetooth), iChat, Disk Utility, Preview, iCal, Calculator, Software Update, Keychain Access, Core Graphics, Core Audio, Core Image, RAW camera image format support, disc burning, and Dashboard and a variety of widgets.

The update also includes all of Apple's security patches issued since Mac OS X 10.4.2 was released in July.