According to whom? To your sensibilities or a specific law? There is no general right to privacy in the U.S. like there is a right to free speech. AFAIK unless there's something in the contract prohibiting it, they're just as free to disclose it as you are to not disclose it. (ianal tinla)

edit: of course, if this is something you feel stongly about, you should just add it to any future employment contract you sign - I imagine most employers would be pretty flexible about this sort of thing.