Much has been said about Yelp’s removal from Google Places as a review/citation source. It’s unfortunate, because Yelp’s review system is unique and assures quality reviews from quality commentators. Google Places offered great exposure for Yelp; people see the reviews, along with a link to the business’s profile page over on Yelp. On the other hand, there’s not a lot of reason for a user to click through to the original review. Also, there’s no real SEO value to the link itself. Yelp’s corporate staff weighed the advantages and disadvantages of allowing Google to repurpose their content and decided against it.
I suspect, however, that Google still recognized Yelp as an incredibly authoritative review source, and just because they don’t appear doesn’t mean they aren’t being considered as a citation and review source, insofar as ranking in the Google Local SERPs is concerned. Don’t neglect your Yelp profile!