First of all, I should say that I am appalled by the use of a selectively edited recording to impugn Ms. Sherrod's character. Racial McCarthyism is racial McCarthyism, and what was done to her was wrong, and to the extent that Mr. Breitbart's involvement in this involved a reckless disregard for the truth or worse, involved delberatley misleading people, he shuld be held in contempt.
Having said that, James Fulford has an interesting article on VDARE where he points out that Ms. Sherrod still is not exactly an unobjectionable figure, even if we have no reason to believe her to be racist.
I also think that his assertion that Breitbart should, under the liberal interpretation of the Constitution, be immunized from libel suits is a very good starting point to discuss the limits of free speech as it relates to relaying deliberately false information, or of information that was deliberately underchecked.
None of which i to say that she should have been let go for the statement she made, or for that matter for any radical political views she might be accused of having; as long as the job is civil service rather than appointed, her political views do not make firing her on false pretenses any more justifiable, nor should she be fired for her views (in the latter case, it would be different if she were a political appointee, e.g. secretary of HUD).
But the idea that she is not radical or objectionable at all may not stand up to close scrutiny.
That is all.