Yelp advertising, does it work?

It certainly seems to have worked for this business. We got the following happy email last week (name, location, and business name altered for privacy):

From: Bob
Date: Fri, Feb 6, 2009 at 9:25 AM
Subject: Los Angeles Store
To: Yelp

Two things .. one how do I get more rotating ads? .. and second we landed an $80,000 a year client yesterday who found us on Yelp. …. When do I do the commercial to tell the world you're the first advertiser to deliver what they promise.

Bob