The CoD4 1.2 patch has arrived, & weighs in at a mere 14MB. It apparently takes care of a left-lean glitch that was reported by the community as well as a few other things.

"This patch optimizes the Lean view offset issue, addressing the glitch reported by several community members and documented and sent in directly by community member GaretJax which is commonly referred to as the "Left / Vertical Lean" Glitch, in addition to preparing files for compatibility with the future release of the Call of Duty 4: Modern Warfare™ Mod Tools."