I mentioned in my review of OpenTable's iPhone application last month that one of the things that they lacked were reviews. Not anymore. Reviews are not available on the iPhone application yet, only the website, but I have to assume that reviews on the application will not be far behind once people actually start writing reviews.
UPDATE 4/2/2009--A representative from OpenTable contacted me and shared that all of there online reviews can be found here. There's actually already a fair number of reviews as far as I can tell.