Get Local Google shows you how.

This summer, Google changed its algorithm so that the search results automatically include local results if relevant:
"We like to make search as easy as we can, so we've just finished the worldwide rollout of local search results on a map, which will now appear even when you don't type in a location. When you search on Google, we will guess where you are and show results near you."
These local results are often displayed above the first regular result on the result pages:

http://www.google.com/local/add/analyticsSplashPage?gl=US&hl=en-US