It's no longer a test: You can now apply Microsoft's complete updates to 32- and 64-bit versions of Windows Vista and Windows Server 2008, in the release-to-manufacturing form. If you've been testing the recent beta of Vista SP2, you will need to uninstall it first from the Programs and Features control panel. From the dialog box on your system, look for update number KB948465, choose that and click Uninstall.
Internet Explorer 8 is not part of this Service Pack. That's not a change from before, though some individuals may rightly be skeptical. Following Microsoft's new policy regarding the marketing and distribution of its Web browser, IE8 is distributed separately.