Information in specific types — including reviews — exposed using microformats, RDFa or microdata has already been used by Google for over 2 years, they call it "Rich Snippets", and it does improve the quality of experience for users, assuming that you equate an increase in clickthroughs to mean that the user percieves that page to be more useful compared to other SERPs results (and anecdotally I always go for results which include rich snippet information gleaned from pages with the required semantic enhancements).

This announcement is not the proposal of a new technique, but rather the extension of one which is already working and is a good thing for the web.