So now, following the lead of other foreign countries such as Germany and Britain, Italy has just brought out its own version, Yelp.it. For now it only features reviews in Rome and Milan, but the listings are already there for other cities (without reviews as yet).
It's in Italian only. As it's written by Italians or at least people who have visited and know Italian, it potentially represents an interesting and valuable resource for travelers. Check it out.