Getting the ACLU involved? Geez. If Tri-Delt's code of conduct is anything like ours (and I'm sure it is), there are very clear-cut definitions of what is and is not acceptable for a sister to do. I'm quite positive that baring yourself for the world to see falls under one of them.
This Playboy bunny needs to turn in her pin and move on. She made the decision to pose naked, and now she needs to face the consequences. Why is the fact that sororities don't want their members to be portrayed as "easy" such a hard concept for some people to grasp?
Did the ACLU get involved when Vanessa Williams had to give up her Miss America title? It's the exact same thing. She had to sign a contract saying that she would do nothing to undermine the reputation of the Miss America pageant. She broke that contract when she posed nude. This chick did the same thing, and I'm nearly positive that her signature is on a Tri-Delt national form somewhere promising virtually the same thing that Vanessa Williams did. So, how is it the sorority's fault that her membership is being revoked?
Take responsibility for your actions, people. And the key word is YOUR.