As some of you may recall, Windows Server 2008 shipped with SP1. Microsoft made this decision in order to synchronize the Windows client and server release schedule. As such, SP2 will be released simultaneously for both Vista and Server 2008. Earlier this month Microsoft put up Knowledge Base Article 948465, a placeholder for both Windows Vista SP2 and Windows Server 2008:
This Microsoft Knowledge Base article will be updated with more information about Windows Server 2008 Service Pack 2 (SP2) and Windows Vista Service Pack 2 (SP2) when the information becomes available. Currently, the product release notes and related information about Windows Server 2008 SP2 and Windows Vista SP2 are not available.
Source:→ Ars Technica