[Air-l] Evaluation Logs

I apologize if this has already been discussed here; I haven't seen it, and have looked through the archive. What thoughts have ye on sites such as http://www.ratemyprofessor.com? Are there legal boundaries to what the site can allow? Are things said there contestable against the author and/or the site? Given relatively small numbers of evaluators per professor evaluated, I would presume there to be negative bias. Interestingly, however, the FAQ for that site in particular claims 60% positive ratings. -eg