The Windows team put up quick work and released the SP2 for Windows Vista and Windows Server 2008 despite the parallel Windows 7 work that has been keeping them busy. So if you are running Windows Vista SP1 or Windows Server 2008, you can install SP2 released from http://www.microsoft.com/downloads/details.aspx?FamilyID=a4dd31d5-f907-4406-9012-a5c3199ea2b3&DisplayLang=en or better turn on automatic updates and it should do the update sometime during this month.
Currently it is available for 5 languages and more general availability might be over the next few months. Note that Windows Vista SP1 is a pre-requisite and it can be downloaded from http://technet.microsoft.com/en-us/windows/bb738089.aspx
In the case of Windows Server, when it was released, it came by default with SP1 so this is technically the Service Pack 1 although, for versioning consistency it is SP2.
The Windows Team proactively blogs about these new releases and other updates at http://windowsteamblog.com/
The particular post which talks about this and the links for other flavours such as x64, Enterprise etc., is http://windowsteamblog.com/blogs/windowsvista/archive/2009/05/26/windows-vista-and-windows-server-2008-sp2-rtw.aspx
For the folks interested in details about this Service Pack, it is KB948465
Cheers !!!