When you leave a question, Google will ping the business owners so they can answer it -- you'll also get notified when your Q gets a reply. Other people can answer your questions, too, though, and you can respond to other people's queries. Since there are bound to be a few substandard responses, Google is implementing a voting system similar to YouTube's, allowing you to "thumbs up" the most useful ones. The highest-rated responses will then be found on top of the pile, so you won't have to wade through garbage to find what you're looking for.