It's getting closer and closer - Trine 2 is hitting stores soon!
IGN prepared a Preview video for this promising sequel - look for yourselves, it's amazing!
Some sources like Amazon list Trine 2's releasedate as beginning December, and even a Collector's Edition seems to be waiting (including the first Trine and the Soundtrack).
Frozenbyte's Joel also dropped some info on the length on the game on the official Frozenbyte forum:
The Trine 2 campaign will hopefully be a bit longer than Trine 1. It's not a whole lot longer though, and it's hard to judge accurately right now. It will probably hover around 6-10 hours for most people. There is a lot of replay value though, especially if you enjoy playing online multiplayer, and there's also all the experience orbs and hidden chests to collect.
We will most likely release at least one DLC campaign after release but that will take a while (perhaps in the spring next year). We'll know more after the game is out and we see all the feedback etc. :)
PS: Not dead, just hibernating.