Microsoft made available for download on November 18 the promised November Community Technology Preview (CTP) build of SQL Server 2008.
The SQL Server 2008 November CTP bits can be downloaded directly from the Microsoft Download site.
Microsoft has been working to deliver more frequent, regular CTPs of SQL Server 2008 to get the product out the door more quickly. But there hasn't been a new (public) CTP available since July. The November build contains a number of new features that weren't part of previous SQL Server test builds.
Microsoft is planning to release the final version of SQL Server 2008 in the second quarter of 2008, after one more CTP release.