Microsoft has released SQL Server 2008 SP1 CU8 (Build 2775). There is no corresponding CU for the RTM branch of SQL Server 2008, since the RTM branch was “retired” on April 13, 2010. I count 18 fixes in this cumulative update, and most of them are for Reporting Services and Analysis Services.

Here is a build list for SQL Server 2008, 2008 R2 and SQL Azure:

-- SQL Server 2008 RTM is considered an "unsupported service pack" 
-- as of April 13, 2010
-- SQL Server 2008 RTM Builds     SQL Server 2008 SP1 Builds
-- Build       Description        Build        Description
-- 1600        Gold RTM
-- 1763        RTM CU1
-- 1779        RTM CU2
-- 1787        RTM CU3    -->      2531        SP1 RTM
-- 1798        RTM CU4    -->      2710        SP1 CU1
-- 1806        RTM CU5    -->      2714        SP1 CU2 
-- 1812        RTM CU6    -->      2723        SP1 CU3
-- 1818        RTM CU7    -->      2734        SP1 CU4
-- 1823        RTM CU8    -->      2746        SP1 CU5
-- 1828        RTM CU9    -->      2757        SP1 CU6
-- 1835        RTM CU10   -->      2766        SP1 CU7
-- RTM Branch Retired     -->      2775        SP1 CU8
-- SQL Azure Builds (most DMV queries don't work on SQL Azure)
-- Build            Description
-- 10.25.9200        RTM Service Update 1
-- 10.25.9268       RTM Service Update 2
-- SQL Server 2008 R2 Builds
-- Build            Description
-- 10.50.1092        August 2009 CTP2
-- 10.50.1352        November 2009 CTP3
-- 10.50.1450        Release Candidate
-- 10.50.1600        RTM