KB 935356 - Cumulative update package (build 3161) for SQL Server 2005 Service Pack 2 is available

Read about it here and request it from PSS if you need the hotfixes that have been released since SP2.

It also looks like they are following the Vista update trend:
SQL Server 2005 hotfixes are now multilanguage. There is only one cumulative update package for all languages.

Unless you are experiencing a specific issue listed inside the KB, I'd stick with the released SP2 build for now.