Lauri Hyvarinen, CEO of Frozenbyte, spoke with 1UP about the game, and revealed a nice chunk of additional information about the game. The Knight, The Thief, and The Wizard will all return and "a bit more color and depth" to their personalities. Additionally, "all three characters have some new abilities, and some old abilities are present in new ways."
When asked about a portable version of Trine, Hyvarinen explained that Trine and Trine 2 require a lot of processing power. It wouldn't be a simple port. The company is not currently considering a Wii or PSP version of Trine or Trine 2.
The new teaser trailer can be seen below.
(NOTE: 1UP video is not currently supported in the GameCenter application)