The official forum thread is at the Infinity Ward forum, but you can click on this link to simply download the file.

Addressed in this update – left/vertical lean offset glitch, and files have been modified in order to prepare for future mods – good to see them thinking ahead already as many players are still whining about non-issues like sniper rifles and such. This patch also includes the 1.1 update which addressed issues that had users losing ranks, profiles and XP when switching from ranked to un-ranked or modded servers.
No apparent issues with the CoD4 1.2 patch yet – I’m keeping my ears to the ground.