A battery killer...
Or, per Verizon propoganda:
Verizon | About Verizon - Privacy Policy
Verizon Wireless collects and uses mobile device location data for a variety of purposes, including to provide our mobile voice and data services, emergency services, and our and third-party location-based applications and services such as navigation, weather, mapping and child safety applications or tools. Where we offer our own location-based applications, we provide you with notice and choice about whether specific location-tracking features available on your phone are turned on.
Many types of wireless applications and services use mobile device location data, including applications provided by other companies and wireless device operating systems. When you are considering new applications or services, you should carefully review the location-based services' or application providers' privacy policies to learn how they collect and use your information.
Verizon Wireless may use mobile usage information and consumer information for certain business and marketing reports. Mobile usage information includes the addresses of websites you visit when you use our wireless services. These data strings (or URLs) may include search terms you have used. Mobile usage information also includes the location of your device and your use of applications and features. Consumer information includes information about your use of Verizon products and services (such as data and calling features, device type, and amount of use) as well as demographic and interest categories provided to us by other companies (such as gender, age range, sports fan, frequent diner, or pet owner). We may combine this information in a manner that does not personally identify you and use it to prepare aggregated business and marketing reports that we may use ourselves or share with others for their use. We may also share location information with other companies in a way that does not personally identify you so that they may produce business and marketing reports. You have a choice about whether your information is included in these reports.
Verizon Wireless does not publish directories of our customers' wireless phone numbers, and we do not provide or make them available to third parties for listing in directories unless you request that we do so.