Microsoft has released a standalone installer for Windows Vista SP2 and Windows Server 2008 SP2 today.
The software giant posted some things to know about the service packs last month, one of the warnings is if "vLite" was used to customize your Windows Vista installation, you may have removed required system components which prevent Service Pack 2 from installing. Microsoft has a workaround for this issue.
Microsoft is expected to post the bits to Windows Update in the coming weeks but if you are eager to install SP2 today then the download links are listed below.