Each player shuffles all permanents they own into their library, then reveals that many cards from the top of their library. Each player puts all artifact, creature, and land cards revealed this way onto the battlefield, then does the same for enchantment cards, then puts all cards revealed this way that weren't put onto the battlefield on the bottom of their library.
10/15/2006 Anything that triggers during the resolution of this will wait to be put on the stack until everything is put onto the battlefield and resolution is complete. The player whose turn it is will put all of their triggered abilities on the stack in any order, then each other player in turn order will do the same. (The last ability put on the stack will be the first one that resolves.)
10/1/2009 Taking it slowly, here's what happens when Warp World resolves:
1) Each player counts the number of permanents they own.
2) Each player shuffles those permanents into their library.
3) Each player reveals cards from the top of their library equal to the number that player counted.
4) Each player puts all artifact, land, and creature cards revealed this way onto the battlefield. All of these cards enter the battlefield at the same time.
5) Each player puts all enchantment cards revealed this way onto the battlefield. An Aura put onto the battlefield this way can enchant an artifact, land, or creature that was already put onto the battlefield, but can't enchant an enchantment that's being put onto the battlefield at the same time as it. If multiple players have Auras to put onto the battlefield, the player whose turn it is announces what their Auras will enchant, then each other player in turn order does the same, then all enchantments (both Auras and non-Auras) enter the battlefield at the same time.
6) Each player puts all of their other revealed cards (instants, sorceries, planeswalkers, and Auras that can't enchant anything) on the bottom of their library in any order.
10/1/2009 Tokens are permanents but not cards. They’ll count toward the number of permanents shuffled into your library, so you’ll get a card back for each token you owned. But the tokens themselves should be ignored while you’re revealing *cards* from your library. In practice, you shouldn’t actually shuffle them into your library since they’ll cease to exist as soon as Warp World finishes resolving. Note that a token’s owner is the player under whose control it first entered the battlefield.