Minecraft is preparing to update to version 1.6, lovingly dubbed the "Horse Update" for obvious reasons. Of course, the patch includes a few other features as well. The official release is scheduled for July 1.
The update notes detail the changes and bug fixes. It adds a horse (of course, of course), along with donkeys, mules. It also lets you use leads for your horses, and "horse armor" for fans of Internet humor circa 2006. Other additions include carpets, hardened and stained clay, blocks of coal, name tags, and hay bales. Texture packs are now "resource" packs so they can also hold sound, and the food meter will be drained if you get healed by a full food meter.
Finally, the notes detail a number of bug fixes as well, like game crashing with a single-frame compass, and being unable to hit mobs while jumping on horses. That last one seems especially important, because if you can't smack mobs around from your mighty steed, what's the point?