Firaxis has released the long awaited v3.13 patch for Civilization IV: Beyond the Sword on Oct 04, 2007. The patch is 121.01 MB in size.
The complete change list is available in this discussion thread.
EDIT2: Direct2Drive version is available.
Download Mirror: Strategy Informer
Civ4 Beyond the Sword v3.13 Patch 2016-10-05
Civ4 Beyond the Sword v3.13 Patch