Nokia Lumia 810 - What is the meaning of the colored dot shown in some of the place icons in Nokia Maps?

The colored dot shown in the upper right corner of a place icon indicates that the place is a prime place added to the map on request by the business owner. In the place details you will find additional information provided by the business owner.

Prime place is a service which lets the merchants to add information of their business to Nokia Maps and have it visible for the Maps users.