As a SharePoint administrator, keeping your SharePoint environment up-to-date is one of the important tasks. Since MOSS 2007 and WSS 3.0 went RTM in November 2006, there are 2 major updates: Service Pack 1 and Infrastructure Update.
The following link summerizes the deployment roadmap for these important updates and provides useful information in terms of understanding and planning for those major updates:
Updates Resource Center for SharePoint Products and Technologies (Powered by Microsoft TechNet)
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