Early this morning (or late last night, depending on your time zone), the SQL Server Release Services team pushed out three new cumulative updates for SQL Server.
KB #2489375 - SQL Server 2005 SP3 CU #14 (9.00.4317)
KB #2489409 - SQL Server 2005 SP4 CU #2 (9.00.5259)
KB #2489376 - SQL Server 2008 R2 CU #6 (10.50.1765)
There are a lot more fixes in the 2008 R2 update - 43, by my count. In comparison, only 9 fixes for 2005 SP4, and only 2 fixes for 2005 SP3. You can draw your own conclusions from that data, particularly if you are still on SQL Server 2005 and are reluctant to upgrade.
And I hate to sound like a broken record, but to reiterate what I've said in other blog posts announcing CUs or service packs for 2008/2008 R2, none of the cumulative updates listed above are eligible for SQL Server 2008 (RTM, SP1 or SP2). I really hope Microsoft takes the confusion they've caused seriously.