SQL Server 2008 SP4 (link) and SQL Server 2008 R2 SP3 (link) have been released. Please note these are the final service packs for these products is now in Extended Support cycle of Product Support Life Cycles.
Update Sept. 30, 2014: Sorry for mistake, for SQL Server 2008 it would be SP4.
SQL2008 SP4 now available
Oops, right, thanks Chris :). Link updated.