TechCrunch has a nice summary of several travel review sites and notes that Yelp has now had 31MM in funding and is rumored to be worth about 200MM. For a company that makes under 10MM per year this seems pretty high, but the Yelp model has been fairly strong in Silicon Valley and Yelp appears to be extending the model to other areas successfully.
I do think Yelp will have a lot of challenges as they move out of their Silicon Valley travel sweet spot. Yelp has done a nice job of connecting people offline who meet online by hosting Yelp parties at Bay Area venues. This probably won’t work as well outside of Silicon Valley where hip young net users are …. not as concentrated, even in the large urban areas.