Shirley Sherrod told the National Association of Black Journalists that she was planning to sue Andrew Breitbart for posting that video clip that gave the impression that she hated whitey.
She is not going to sue Andrew Breitbart. When she does get around to talking to a lawyer, she will be told of a 1964 Supreme Court decision called NY Times Co. v. Sullivan. This ruling set very high standards for a public figure to sue for libel. A good example of how this ruling works today is the National Enquirer-style tabloids (George Bush is drinking again! Oprah is on her deathbed! John Edwards cheated on his wife! - wait, that last one is true.) get away with publishing absolute fiction.
What would make this worth the price of admission is when Breitbart's lawyer gets Sherrod under oath during discovery. The more Sherrod appeared on cable the week after her firing, the more apparent it became that she does hate whitey. Which is why she wasn't on any of the Sunday news shows. After her performance on CNN the media didn't want to give her any more rope.