Several years ago I was in a room with Chuck Davis, then CEO of BizRate (Shopzilla), and pitched him the idea of including local, offline store information in the company's database. He cited the complexity of getting the local information and the absence of a competitive need for it at the time. Times have changed and local (together with "social shopping") is the next frontier for comparison engines.
A range of competitors, including NearbyNow, ShopLocal, Yokel, Become, CNET and Froogle (and soon more newspapers), are offering some version of local, offline shopping data and inventory information to consumers. And today Yokel announced expanded local store and inventory information in the San Francisco Bay Area.
Here's more information from my blog.