Since its launch earlier this year, Google Maps has drawn immense interest from outside developers who have extended the service for applications such as finding the cheapest gas to locating apartments for rent. But these add-ons, or hacks, were never officially sanctioned by Google - until now.

On Wednesday, the Google Maps API was unveiled to developers looking to embed Google Maps into their own Web pages using JavaScript. The toolkit also enables users to build their own map overlays, such as markers and shadowed "info windows" just like those used by Google.

"Developers are already using Google Maps on their websites in an ad hoc way. Google wants to help these developers and others by providing support and documentation for their innovations," a Google spokesperson told BetaNews.

The API, or application programming interface, is available to any Web site -- commercial or personal -- that is free to consumers. The service is currently in its beta phase, and developers must first sign up to register their Web site.

Google had previously released APIs for its Desktop Search and AdWords products. But while those offerings clearly bring in advertising revenue for Google, some mystery has remained as to how Google will profit from its maps service. The company offered a hint of its future plans on the Google Maps API Web site.

"Google reserves the right to put ads on the map in the future, and you may not alter or obscure these either," reads the terms of service for the API.

Google has also imposed some minor restrictions on how its maps may be used by third parties. "We do not want to see maps that identify the places to buy illegal drugs in a city, or any similar illegal activity. We also want to respect people's privacy, so the API should not be used to identify private information about private individuals."