The last new entry to the Trine action-adventure-platformer series was with Goblin Menace in 2012, an expansion for Trine 2, which itself came out in late 2011. So yeah, it's been a pretty long time, and it looks like Trine 3 is right around the corner... ish.
Trine 3: The Artifacts of Power will star the trio of main characters we're all used to -- Zoya, the archer and acrobat, Pontius, the knight, and Amadeus, the wizard who summons boxes and can levitate things. The press release mentions an "initial" release on PC for this year, but since Trine 2 eventually hit quite a few home consoles, it's probably safe to say that the third game will too. Here's a trailer, showcasing some lovely visuals:
Loving the new camera angles/3D movement. Great animation quality, too. Here are some screenshots (don't forget to check out the one at the top):
Trine 3 will be out on PC sometime in 2015.