The ACLU of Northern California says it’s time for a privacy check-in on location based-services. Their handy chart compares several of the most popular location-based services along a number of dimensions.
Little of what they examine has to do with civil liberties—cough, cough, ahem (this is a favorite critique of mine for my ACLU friends)—but the report does find that five out of six location-based providers are unclear about whether they require a warrant before handing information over to the government. Facebook is the winner here. Yelp, Foursquare, Gowalla, Loopt, and Twitter are unclear about whether they protect your location data from government prying.