According to the post, the entirety of Pathfinder Online at launch will take place in a 133-square-mile region known as the Crusader Road area. To get an idea of how absurd this is, look at this post's header image. See that little red box? That's the Crusader Road area. And the remainder of the map that it's shown on is only a small fraction of the entire Pathfinder world (as an image on the blog post shows), so players should likely expect a lot of exploration in a massive-scale world. For the full details on Crusader Road, head on over to the Goblinworks official site and take a look.