When you Google something, it takes the zip-code of your IP Address into consideration.
So if I'm at college in NY and google "cupcakes" I get a bunch of pastry and bakery places, along with the grocery store and Dunkin' Donuts, then a blog about cupcakes and Martha Stewart's recipe for cupcakes. But if I set the zip code to my home in NH, I get a bunch of different bakeries, including ones that I've been to before.
Your client wants people around him to know his business/site is where locals should go to. No use if he gets a high national search result if he doesn't ship cupcakes, for example. So I'd include info on his site about how he's local. Like "First bakery in Springville" or something, or that he's won local awards, been featured in news papers, etc.
If you have twitter, you could shoot my PR professor a message, he should be able to show you information to help you out:
https://twitter.com/#!/mikefixs