PopCap brought WoW into Peggle last year and now Blizzard made a response to PopCap. They just added something that you are quite familiar with into the Beta server of Cataclysm, a Plants VS Zombies-like mini-game. Check out the video below. You surely don't want to miss the quest that can be found in the Hillsbrad Foothills.
Great changes will be seen in Azeroth in Cataclysm, but do you think this is one of the great changes? It's actually a series of quests, where you can unlock different plants like peashooter and sunflower as you go on. You can get EXP, gears, and a sunflower pet as rewards from the quests.