Five-seven

The Five seven is a semi-automatic pistol that is set to make an appearance in Call of Duty: Modern Warfare 3. It seems to be the default weapon for Survival Mode.

Multiplayer
The Five seven is unlocked at Level 58 in Modern Warfare 3's multiplayer.

Survival Mode
The Five seven is the starting weapon for every match of Survival Mode.

Trivia

 * The reload animation for an empty magazine shows the slide being pulled back to unlock the slide release lever, as opposed to just pressing the slide release. It shares this trait with the G18 from Call of Duty: Modern Warfare 2 and the CZ75 from Call of Duty: Black Ops. 
 * It is held in one hand, similar to that of the G18 in Call of Duty: Modern Warfare 2 and the ASP in Call of Duty: Black Ops.