I also think that a blog is just as important (maybe more-so) for acquiring and keeping local customers as it is for spreading the word globally. I often ask people to think about how they themselves pick companies to do business with. Usually it starts with a Google search and then further online research to try to get to know the companies a little better. People search for a local business no differently. Not only will your blog boost your Google rankings, it will allow your potential customers to get to know you and personally connect with you before they walk in the door for the first time.