Zoo has recently seen quite a bit of success on the Pro Tour scene, placing 2nd at Pro Tour: Honolulu. It was piloted by the "cursed" Craig Jones. Zoo adopts an approach closer to the classic Sligh deck than anything else. Early 2-power one-drops (Kird Ape and the dreaded White Weenie duo of Isamaru, Hound of Konda and Savannah Lions, plus the newly added Wild Nacatl, easily a 3/3 for 1) are backed up by a powerful two drop (Watchwolf). Interestingly enough, the deck does feature a three-drop permanent, Burning-Tree Shaman. More than likely the power of the Shaman gave him the slot over Scab-Clan Mauler, who would almost always be a 3-power two-drop, but lacks the killer triggered ability on the Shaman. In another interesting choice, Jones main decked three Kami of Ancient Law. Enchantments are becoming increasingly powerful and popular in Standard, so having main deck ways to remove them is quite good. Having that ability wrapped up in a Bear is just gravy.
Like other Sligh style decks, most of the creatures exist to put the opponent in reach of burn, though Zoo's creatures generally stick around longer than most Sligh build creatures. Zoo features the most powerful burn suite found in Standard today. Lightning Helix, Shock, Char, and Flames of the Blood Hand are all featured, so there are a ton of both creature elimination, as well as player elimination options.
Zoo sacrifices some of the mana consistency of its cousin, Heezy Street. The mana base is heavy on non-basics, so it's very vulnerable to Blood Moon (not to mention pricey).
Zoo simply demolishes Owling Mine, and has fairly good matchups versus both aggressive and controlling strategies. Umezawa's Jitte and Hunted Wumpus in the sideboard bolster Aggro matchups, and Giant Solifuge and Flames of the Blood Hand bolster Control matchups. Guerrilla Tactics is excellent against the floods of Orzhov Aggro that were in Honolulu, and Tin Street Hooligan provides some additional utility.
4 Kird Ape