There have been a few recent cases where people were arrested for using open (or even free) wireless connections. In the linked article, a man parked in front of a coffee shop and used its open wireless connection without going inside or purchasing anything. In another case I read about, a man found an open wireless connection in a residential neighborhood, and accessed it from his parked car. A police officer got suspicious and arrested him. The applicable laws about unauthorized access can be stretched to cover this type of situation. So the moral of this story is that even though the wireless connection is wide open, it’s still illegal to use it without authorization of some sort. And in Michigan at least, it’s a felony offense.