I've seen some of the therapist reviews on Yelp. One of mine and my psychiatrist are reviewed on there.

My problem with Yelp reviews - or Google, or whatever site - isn't about protecting the therapist. It's that online reviews of any medical or mental health professional are pretty useless, in my opinion. People either love their doctors or hate them, same goes for their therapists. In fact, all online reviews, since the participants are self-selected, have to be taken with a large grain of salt. If there's a significant number of reviews that all trend negative or positive, that's more useful, but there rarely is. So the way I see it, Yelp reviews have the potential to do the client a real disservice if they are the basis on which a therapist is overlooked or chosen.

I imagine Yelp has some feature where you can add a business to review. I actually wouldn't do it because no way am I risking my confidentiality, but others obviously feel differently.