It addressed several connectivity issues and balanced certain character classes (like the Rifleman and Sniper).
Depending on what you are looking for, here is the essential info regarding that specific version: What’s New in v1.1? File: Call.of.Juarez.Bound.in.Blood.v1.1.zip ...
Some ZIPs with this name contain modified executables to run the game without the original disc. To help you better, let me know: Are you trying to fix a bug or crash in your game? File: Call.of.Juarez.Bound.in.Blood.v1.1.zip ...