Microsoft has also released SQL Server 2008 SP3 Cumulative Update 4. This is Build 10.00.5775.00, and it has ten fixes listed in the public fix list. Remember, this Cumulative Update is only for SQL Server 2008 SP3. It will not work on other Service Pack levels of SQL Server 2008, and it will not work on SQL Server 2008 R2 (which is a newer major release of SQL Server). This Cumulative Update was actually released on March 20, but the URL for the public KB article was not working reliably until later that day.
Also, keep in mind that Cumulative Updates are, as the name implies, cumulative. That means you could go from SQL Server 2008 SP3 RTM, directly to SQL Server 2008 SP3 CU4 without having to install any of the earlier Cumulative Update packages for Service Pack 3.