Every war plan begins with the unfurling of a map. Google’s designs on Europe are a little clearer now that the search engine has released test versions of Google Maps for France, Germany, Italy, and Spain.

The map products of Google and its rivals, Yahoo and Microsoft, are an important part of the burgeoning local search business, which the search engines regard as one of the last untapped reservoirs of ad revenue.

The Kelsey Group predicts that the U.S. local advertising market will hit $124.8 billion in 2010. In 2005, it grossed $96.8 billion. U.S. local search and classifieds revenue is seen jumping 25 percent to $9.9 billion in 2010 from $3.3 billion in 2005.

Matt Booth, an analyst with the Kelsey Group, says that maps are the shock troops in a campaign to win advertising dollars from the local market.

“Mapping is the forefront of a local strategy,” he said.

Google’s improving of its map product in Europe, announced late Wednesday, follows Yahoo’s debut of satellite images on its beta map site on April 11. In October, Google announced the launch of Google Local, which blended mapping data with local information such as restaurant reviews, addresses, and movie times.

The move also came one day after French President Jacques Chirac said his country would spend $2.5 billion on six technology projects including a search engine designed to compete with Google (see France’s $2.5B Tech Foray).

Like Google Maps and Yahoo Maps, the beta version of Google Maps in the four European countries comes with an API (application programming interface) that allows programmers to incorporate Google Maps into web pages not connected with Google.

The API has generated a cottage industry of mashups that combine Google Maps with content that ranges from real estate to fast food finders.

Mr. Booth said that the power of maps and local advertising has not been fully exploited.

“The real revenue opportunity comes when there is rich content underneath all of the pins on the map,” he said.