Reading the paper posted at https://www.datenschutzzentrum.de/facebook/facebook-ap-20110... it seems if he finds a judge who understands it he could very well get an injunction prohibiting websites from deploying a working like button to german users. Failure to comply would result in a fine of 50.000€ under current law. Of course it would only be enforceable on websites hosted in germany. I don't agree with his assertion that he can apply the german TMG (TeleMedienGesetz) to Facebook since they have no hosting presence in Europe, as far as I know. And even then there would still be the trouble of enforcing it.
I actually think that would be a good thing, I don't like being tracked through the like button if I forgot to log out.
