The game formerly known as Project Eternity will arrive on GOG, Steam and "other online retailers." Between now and the release date, Obsidian will be working on polishing, squashing bugs and the "finalization of … everything," including backer rewards.
Pillars of Eternity was originally slated for a spring 2014 release. After it ended its Kickstarter campaign in October 2012 with $3.9 million — more than three times its $1.1 million goal — Obsidian expanded and delayed the game. Previously scheduled for a winter 2014 release, Obsidian delayed the RPG last October to "incorporate as much feedback as possible, polish every nook and cranny of the game, and make sure we don't ship a buggy game."
For more on Pillars of Eternity, which is in development for Linux, Mac and Windows PC, be sure to watch the Overview episode below, where we play through the backers-only beta.