Fans of Angry Birds, rejoice, as Angry Birds HD for iPad has just been updated. The update, released by developer Rovio earlier today, adds a slew of additional levels to the award winning game. The update also brings a new bird, the Mighty Eagle, a powerful bird able to clear the level of your choice. Note that while the update is free, the new bird is not, as it will cost you $0.99, via an in-app purchase. The update brings 15 additional levels to the game, all wrapped in a new theme called Frontier Badlands, as well as a new Golden Egg level, and a good amount of new achievements. And for the folks who haven’t played the game in a while, the new release also includes all the goods brought by the previous updates, with more than 60 new levels added to the game since its launch. Thanks to the developer’s constant updates, Angry Birds has proved to offer an incredible replay value. The game is so popular that even iPhone 4 cases and plush toys are now available online (see here). If you already own the game, the update is free. Otherwise, you can download the game here for $4.99.