Google yesterday officially launched its free, three-dimensional satellite mapping technology - Google Earth - which the San Francisco Chronicle termed "part flight simulator, part video game and part world atlas." It allows users to find businesses, get directions, and share the information with others. Google is using Google Earth and Google Maps to go after local advertising, a market that in the U.S. could reach $3.4 billion by 2009 according to the Kelsey Group, writes Bloomberg News.

The official launch of the new Google service comes as MSN unveiled its own local search tools - and a month after Google first revealed the new technology.

Google Earth comes in tiers, ranging from free for the basic version to $400 a year for commercial use. Only Windows-based desktop computers newer than four years old and desktops not more than two years old are compatible, and Google is working on a Macintosh version.

Google obtained satellite imagery technology last year with its acquisition of Keyhole, a digital mapping company. It has since then been working on combining search with mapping.