Through June 30, 2010, customers using applications that are not yet
certified for use on SQL Server 2008 Standard, a copy of SQL Server 2005
Standard will also be included in SBS 2008 Premium. SQL Server 2008 (or
2005) Standard can be installed on either server: If you install SQL on
the first server then you must install the management tools on another
machine.
SBS 2008 Compare Features:
http://www.microsoft.com/sbs/en/us/compare-features.aspx
----------
That used to say December 31, 2009 as the cut off date. Now it says June 30, 2010. Thanks to the SBS team
for listening to a request to extend the automatic downgrade rights for SQL.