The Cumulative update package 3 for SQL Server 2008 Service Pack 1 (Build 10.00.2723) is available:

http://support.microsoft.com/kb/971491/en-us

And here you can get the whole information of builds that were released after SQL Server 2008 Service Pack 1 was released:

http://support.microsoft.com/kb/970365/en-us

CU tosc