Yes it has been confirmed for quiet some time now. You seriously didn't see anything about horses. Ha, uhhhh ok... well heres your confirmation to horses and everything else. Next time look there, it always has news on updates. And to really answer your question, no one knows when a update comes out until 4J announce it.
Edit: Id like to point out that there is indeed horses in the picture link the squid dude provided, you had to look in the background and not just in the center lol.
― Ilya Pasternak (Strigon 1 new)
I scored 100% on the Minecraft Trivia Quiz. How much do you know about Minecraft?― Ilya Pasternak (Strigon 1 new)
http://www.minecraftforum.net/forums/minecraft-xbox-360-edition/mcx360-recent-upcoming-updates/2064204-official-minecraft-xbox360-twitter-update-thread
Edit: Id like to point out that there is indeed horses in the picture link the squid dude provided, you had to look in the background and not just in the center lol.