Did it eventually load? Or did it hang there until you force quit the game? It is regenerating the world when you load a game, so it should take the same amount of time as running the game for the first time.
Darn. Must have had some kind of error during world generation. I moved it to another thread to make loading easier for multi-core systems, but that means I don't get errors the same way. I'll see what I can do about tracking down issues like this easier.
