Are there any way of changing the language of the subtitles? It's in norwegian, and norwegian doesn't belong in games :P (And text btw.. everything of text is in norwegian... godamnit)

Im not sure, but try changing your consoles system language to english. 
 
hope you can solve it. 

It should work setting your profile to a UK one. I did when I played "Nuts and Bolts" and "Viva Pinata". For some reason those games have Norwegian voice actors if you are in Norway. It is awful. Norwegian actors and voice actors always sound like they are doing theater. In a bad way.
So change your profile to a UK one. The only downside of this is that people will think you are from the UK...
 
I don't have the game yet, so cannot try it. Will probably have to wait two weeks for my Black Edition to arrive from Play.com

I've figured out how to do it.
 
Start menu -> Run
Type regedit
Go to the folder HKEY_LOCAL_MACHINE\software\ubisoft\Assassin's creed II
There's a value named Language, double click it and type English.