megahurt writes "Location-based services are becoming more common, and the features they add to mobile devices can be useful and even fun. But the downside is that everyone who reads the posting will know the user isn't home. On top of that, some services, such as Foursquare, can be linked to Twitter feeds. Peter Eckersley, senior staff technologist, says there are many situations in which the location data that is kept could be misused. Many of the providers of services say in their privacy policies they will give up the data in cases where it is subpoenaed. That isn't always from law enforcement; sometimes the data can be used in civil lawsuits such as divorce cases."