Most admins are familiar with the process of downloading and applying Service Packs for servers and desktop systems. These downloads, of course, provide hotfixes and security updates that help to keep your systems current. Sometimes, however, a service pack includes something more. This is the case with the release of Microsoft Exchange Server 2007 Service Pack 1, which includes many exciting new features.
For a detailed look at all the changes, see "What’s New in Exchange Server 2007 SP1" at technet.microsoft.com/bb676323.aspx. However, for a nice overview from Tony Smith, check out his coverage over at TechNet Magazine: http://www.microsoft.com/technet/technetmag/issues/2007/12/SP1/default.aspx