Ocelot

Ocelots are a passive mob, due to be introduced in Minecraft 1.2 The mob was first implemented in snapshot 12w04a. Ocelots will only spawn in jungle biomes.

Behavior
Ocelots are the first mob to sprint, their behavior seems to be shy, as the ocelots will sprint away from the player once it gets close, and will stop sprinting and walk normally once far enough away. If walled up they will stand still, and sprint out the nearest hole when one has been made.

This behavior will stop once tamed.

Standing still a few feet from an ocelot while holding a raw fish will cause them to turn and face you and start to very slowly approach you, once in this mode, as soon as they are close enough, right-clicking them to give them the fish will tame them and they will transform into one of three different possible pet cat skins and will follow you, similar to a tamed wolf.

If you move around or move your cursor too quickly while the Ocelot is approaching you, it will get scared and start running.

Wild ocelots will occasionally slowly sneak up on chickens and pounce. The two player-related behaviors (fleeing from and slowly going towards for raw fish) appear to take precedent over chicken hunting.

Ocelots can't breed, though if you tame them into cats they can breed.

This video contains a good general overview of the Ocelot's looks and behaviour

Bugs
Ocelots become stuck in fencing if they run into it. This happens especially when they are chasing chickens. 

Simlar to wolves, when Ocelots go onto or into non-solid blocks, the spin around on them. This is most likely a pathfinding AI bug.

Gallery
Ozelot Ocelot Оцелот