With today launch of the August Modern Warfare 3 DLC drops for Xbox 360 Elite members, Infinity Ward has also introduced Title Update 20 or Patch 1.20 for Xbox 360. The new Spec Ops mission, Light ‘Em Up & Special Delivery as well the new Chaos mode, are available for all Xbox 360 Elite Premium members and will be available for non-Elite Xbox 360 players to purchase from Thursday August 9, as part of Content Collection 3: Chaos Pack.  

Please find below the official patch notes and make sure to check out the Black Ops 2 multiplayer reveal trailer, which released today.

• Support for Elite drops 19-24
• Matchmaking improvements to use first party country if DML data isn’t available
• Additional logging for matchmaking
• Update to Face Off spawn logic
• Added logic to make Terminal count as an original map
• Fix for XM25 challenges not registering properly
• Fix for exploit that allowed change of a UAV into a second Ballistic Vest

Source: Call of Duty forums