actually, you're not (Score 2, Informative)

While you might be allowed to leave and join a different club, it's not free.. the IRS can still demand you pay income taxes for the next ten years, even if you renounce your US citizenship. While they might not send the goons to go kidnap you and bring you back, the next time you visit the US (say, for a family funeral or a friend's wedding) you can expect to be met at the airport. Search for [expatriation tax].