Google has switched on another search-related ad revenue source, this time on Google Maps.
Some searches, such as those for taxi, restaurant, or hotel, show a blue-background text ad along the bottom of the Google Maps page. Given that anyone at the site is using a map, this is an opportunity for Google to employ a strong geographic influence in its ad targeting algorithm, and in general, the better targeted an ad is, the more effective and costly it is.
The results vary according to what the user sees on the map; for example, searching for "notary Kansas City" shows no ad, but centering the map on Kansas City then searching for "notary" does. Likewise, "shoe store San Francisco" shows results but "shoe store" while looking at San Francisco doesn't. Presumably this behavior will change according to what keywords advertisers bid on.
The company already showed some sponsored "pushpin" links that appear on Google map results.
Google makes the vast majority of its revenue from text ads that appear next to search results. Searches are a great way to discern exactly what people are interested in, which improves targeting.
In all likelihood the Google Maps ads also require payment only when users click on the ads, a more measurable method of paying than exists for most graphical "display" ads.