It looks like Trine is making a transition to the less-known gaming platform known as the Mac. Frozenbyte released an official announcement on their community forums that they'll be using Steam for Mac to release, and people with PC version of the game will be able to play on their Mac if they so choose.
Trine is coming to the Mac platform in November 2010. It will debut on Steam (as a SteamPlay title) but it will also be released on other digital distribution channels later this year (hopefully)
Mac users will enjoy playing the beautiful Trine alongside their PC counterparts at last.
Source: Frozenbyte.com