The downloadable content will be coming to Steam for PC and Mac users on September 6th for the price of $7.99 (€6.99 for Europe). If you have the collectors edition of the game you will already have access to the first two levels of the expansion pack, these levels in the beta will disappear once the content actually releases.
For gamers who want to purchase the DLC in the App Store or on Linux will have to wait a little bit longer for the content to be released. If you are planning to buy Trine 2 on the Wii U, the game will come with this additional content already included. Whether you want to play the content or not you will have to download a 2GB patch to make sure that the game is compatible when you play online.
The content launches September 6th on PC and Mac.