Landmarks can be extremely valuable for navigational purposes, and for this reason Google add icons for prominent businesses and points of interest on Google Maps as you zoom in. These business icons can be clicked to view additional information about the business, such as the rating, address, and phone number.
Google says that, "We will shortly be adding these clickable business icons to the Maps API v3 as well."
"If your application does not specify a specific version of the Maps API to load these icons will appear on the map by default from early next week, unless you are a Maps API Premier customer. The business icons will be classified with the poi.business Styled Maps feature type. If you would prefer that your Maps API application not include these icons, you can remove them ahead of next week's release by setting visibility:off on the labels element of poi.business for your map. Maps API Premier customers who would like their maps to include these icons can enable them today by setting visibility:on," explains Thor Mitchell, Product Manager, Google Maps API.
"In order to allow you to control visibility of these icons, and other features, across all the default map types, you can also now specify styles for your map in MapOptions. This enables you to selectively restyle roads, labels, and other features on Hybrid and Terrain maps in addition to Road Maps. Note however that the base satellite imagery (for Satellite and Hybrid maps) and base relief imagery (for Terrain maps) cannot be restyled," Mitchell added.
You can preview these icons, and the InfoWindow that is shown when they are clicked, on the map below:
[Source: Google Geo Developers Blog]