Not too long ago Google's Adwords started offering GeoAds -- a low cost-per-click way of advertising your businesses on Google Maps. Now they've extended this service to all business owners who wish to see their company appearing on Google Local, for free (albeit without the fancy icons available to paid listings).
After completing the process of describing your business (address, opening hours, description, and contact details) you select the categories that describe your business. Then once Google has confirmed a business exists at the premises specified (via phone or mail) you're in!
This is an obvious and necessary step for Google Maps / Local which has so far been relying on commercial listings (like Yell) and by scouring web sources. Now owners can specify details for their business directly -- which is probably bad news for the aforementioned companies, but good news for small business.
With the ability to specify details like web, email, opening hours, and payment methods all at no cost, it's certainly a much better deal than most of the 'traditional' business listings (like the Yellow Pages) currently offer.