In Ghost Recon: Future Soldier for the PS3 and Xbox 360, it is possible to melee / knife someone for special animated kills.
In order to melee someone, you have to get close to them and wait for a prompt to come up on the screen at the bottom. Once you see it, press the action/reload button to perform the melee and kill your target instantly.
This won’t necessarily be as easy as it is in other games, so don’t go thinking you can run around Commando style killing everyone by hand.