Google launched blue location markers in to Adwords ads and tie them to the same colored marker on the adjoining map to make your listing stand out amongst the other businesses.
Google has been playing with what they call "location extensions" since 2009 in various forms. "Today, we're introducing a way for your location extension-enabled ads to show directly on the map. We'll be integrating information from ads with location extensions into the Place Search map on Google.com. On the map, your location will be marked with a distinctive blue pin," the Adwords blog reported.
The markers were launched outside the United States as well, one of the forum members from Australia brought this to my attention.
In order to have the blue marker appear you need to be in the top area of the search results. As Google explains the marker "will appear in this new integrated format whenever we infer that a potential customer is looking for local information and your ad qualifies to appear above the search results."