Google has opened Google Maps to the world to annotate: It's your world. Map it.
Now in the U.S., Australia, and New Zealand, you can log into your Google account to edit a place on the map. You can even mark that a business has closed to save someone an extra trip. Of course, we've taken steps to help protect accuracy -- for example, you'll still be able to see the original listing information along with the history of changes made.
That is so impressive. Google has taken a very successful product and turned it over to the people as a wiki. That takes guts. My hat is off to Google!