If a french or german court decides that a foreign company is violating their laws, they can do little besides preventing them from reaching their market, which would in this case mean that they can order ISPs to block the site. I'm pretty sure that there is no way that they can actually make a foreign-based company abide by their laws. How would they enforce the ruling?

Of course, if the company in question also owns a EU-based daughter company through which it operates on EU market (as Facebook apparently does), then that's a whole different ballgame.