Google is giving geo map developers a new option to earn revenue from their Google Maps API implementation. Dubbed Maps Ad Unit, this new Google Maps feature is part of the AdSense for Maps portfolio, which allows developers to overlay AdSense units over a Google Map which they have embedded on their sites. 
Ads on Maps Ad Units are targeted to the maps view and updates as a user hovers around the map. To set this up, Google maps developers and users should link their Maps API implementation to an AdSense account to earch from this new online ad revenue scheme.
Adding the Maps Ad Unit to your site is easy. You simply need to create a GAdsManager of style ‘adunit’. You will also need to link this Maps Ad Unit to an AdSense account. If you don’t yet have an AdSense account, sign up for an account. Once you have done so (or if you already have an account) make sure you’ve also enabled the account with AdSense for Content.
Maps Ads unit can also be repositioned anywhere within your map by simply specifying an alternative GControlPosition.
As this ads are location-specific, AdSense Publishers stand a good chance of generating revenue specifically because users would find those Maps for Ad units more helpful than the regular, generic AdSense ads.
Here are some implementations of the Maps for Ad units- Acme Mapper and ZipMaps.
