In PvP, this new option will create a whole new level of positioning and feinting using one's pet. If the enemy team is training your pet, you can tell it to run behind a pillar. In PvE, you'll be able to guide your pet out of fire, set it to a more appropriate position or otherwise make it act like a beast that obeys your commands. It's going to be pretty awesome; I'm likely to spend my first few hours learning a bunch of stupid pet tricks.
Right now, the actual icon for the Move To command is missing, but the button still works.
World of Warcraft: Cataclysm will destroy Azeroth as we know it. Nothing will be the same. In WoW.com's Guide to Cataclysm, you can find out everything you need to know about WoW's third expansion. From goblins and worgens to mastery and guild changes, it's all there for your cataclysmic enjoyment.