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Although the privacy issues surrounding Facebook's new, opt-out only data sharing policies are making people uncomfortable, one area where folks are apparently happy to have their private data shared is on their mobile phones. And by private data, we mean exact GPS coordinates. Coordinates that are shared with software developers, ad networks and location-based service providers in return for free location-based mobile applications and geo-targeted ads.

In fact, one in four U.S. adults use mobile location-based services, according to a survey put out by the Mobile Marketing Association (MMA) last week. And nearly half of those users are responding to the included location-based ads.

Tomorrow, Motorola will announce that it plans to replace Google's location services on its Android phones with Skyhook's location engine. By default, all Android devices currently use Google's own location services to determine a phone's location based on GPS data from the phone and the location of nearby Wi-Fi access points and cellular towers. Skyhook, which pioneered this method to determine a device's location, made its name as the default location provider for Apple's iPhone and desktop operating systems. Adding Motorola to its partners will give Skyhook a strong foothold in the booming market for Android phones and applications.

While services like Gowalla and Foursquare still haven't become household names outside of the early adopter market yet, the technology behind these apps is now solidly mainstream. According to a new survey by the Mobile Marketing Association (MMA), about two thirds of iPhone owners now user location services at least once a week. Taking all cell phone users into account, 22% of adults between 25 and 34 use location services at least once a week, mostly to locate nearby points of interests, shops and services.