Have you downloaded it? This is verbatim from the Technet email
SQL Server 2008 has been released and is ready to deliver a rich set of integrated services that enable you to do more with your data, such as query, search, synchronize, report, and analyze. MSDN subscribers can find RTM versions now available for download. Visual Studio 2008 Service Pack 1 offers VS 2008 and .NET Framework 3.5 users improvements in responsiveness, stability, and performance. Visual Studio 2008 Service Pack 1 and .NET Framework 3.5 Service Pack 1 downloads are now available to MSDN subscribers. SQL Server 2008 evaluation versions are available for free download as are free downloads of SQL Server 2008 Express and SQL Server Compact editions.