Google announced on Google+ that they've expanded more AdWords ads to the Google Maps desktop and mobile app interface.
Now they may show ads within the search results for places like restaurants and hotels in a list view below the search box.
The ads will show additional information pulled from your ad extensions, such as phone number for your ads using call extensions or locations extensions showing data like ratings, store hours, and the Street View image of your business.
Here is a screen shot of how the ads may look. This comes shortly after Google added a scroll option to the listings, which now makes even more sense because you'll need to scroll to potentially see organic listings now.
More details at Google help.
Forum discussion at Google+.