Google employees confirmed in person today plans for local advertisements within Google Maps, including their Web APIs. Google will overlay blue markers on the map to highlight local business advertisements directly within the graphical search result. A corporate logo and advertising message will be displayed inside of marker info windows complete with a paid link. API developers will have the option to display the ads or to signup for a commercial relationship with Google.
Combining local search targeting with graphical ads should yield extremely high payouts for Google. Google is currently paying data fees for maps used in a variety of mashups and I was glad to hear the company has some plans to monetize the experience. Google has just started a new developer relations group to interface with outside developers using maps and other APIs in their applications so I expect improved future communications.
The Google blue marker experience was previously spotted and reported by sites such as ClickZ a few weeks ago when Google first started testing the idea but no one at Google would confirm their plans at the time.