|XP - 3|
|Drop - ?|
|Attack - N/A|
|Spawn - Daytime in open/flat space mostly|
These creatures can be called Rabbits or Bunnies. They are officially called bunnies.
Bunnies are passive mobs that can spawn in any open space, and can be tamed by picking them up and letting them ride on your head. While the bunny is on your head, you are unable to go through walls that are 2 blocks high because it harms the bunny, however if you crouch while going through a door way the bunny does not get hurt. While riding a Horse, this results in a significant speed boost. If you are being chased by mobs, and you drop the bunny, the mobs will target the bunny instead of the player.
Bunnies can be bred by placing two tamed bunnies of any colour in the same enclosed area. They will then breed, spawning 1-7 new bunnies. These bunnies don't always look like the parents though. As they reproduce quite rapidly, you should keep watch of your bunny breeding programs as to not cause game lag or overflow. It should take 5 minutes(half a minecraft day) for them to start having the babies.
Source - Minecraft Forums