There might be an exception for a business when a very small, insignificant portion of its activities reach into US borders. But no way would Bitstamp fall into such an exception. I doubt any exchange would, considering the vast, vast majority of trading is by US citizens.
Think about it. If physically setting up shop on foreign land is sufficient to evade US laws, then why don't we see more foreign businesses selling dangerous products (exploding barbie dolls) or openly offering money laundering to US citizens? Laws and treaties. Dummies.
Bitstamp and BTCe going down by the end of the year, for sure. If you don't have your coins/fiat on Gox or CampBX, may as well just kiss them goodbye.
Cool story bro, tell it again.