Did anyone notice that animals are now permanent (and finite)? No animals were spawning on my island so I went to a nearby landmass and sheared some sheep so I could make a bed. When I passed through that area again about an hour later I saw shorn sheep running through the land. To test this, I collected a bunch of eggs left by chickens in that area, brought them back to my island, built a pen and threw the eggs until a chicken popped out. The chicken never despawns. I even left the island for half an hour once and when I came back the chicken was still in its pen. It seems like the new passive mob spawn mechanism is in 1.8 even though mobs can't breed until 1.9.
(You can kind of breed chickens by throwing eggs though.)
It might be wise to survive on a diet of bread and fish until 1.9 comes out, otherwise we may drive the all the animals to extinction.