Actually, the way it works is that Google has an app that you have to use before approaching a business. It basically indicates whether or not that business has already been approached; if it has, you're not supposed to try to sell them again. Also, some of the other photographers in the area may lay claim to entire industries. For example, one guy in my city pretty much had all of the new car dealerships stitched up.
The big problem is that businesses are not very receptive to the idea because they don't see how it will really benefit them in terms of making more money. It would be nice if you could go in with a bunch of Google swag that might impress them, but Google gave us absolutely nothing in terms of credentials -- not even a lousy t-shirt. Now things may have changed, I don't know. But when I was in it, the whole program was still in a kind of test phase to see whether or not Google would continue to support it.
If anyone is thinking that joining the program will be easy money, I think you'll be disappointed. Most of your time will be spent cold-visiting businesses.