Many of the iPhone apps are uploading your address book data when you use them.
:source: Source: Venturebeat.com
Full story at the source.Facebook, Twitter, Instagram, Foursquare, Foodspotting, Yelp, and Gowalla are among a smattering of iOS applications that have been sending the actual names, email addresses and/or phone numbers from your device’s internal address book to their servers, VentureBeat has learned. Several do so without first asking permission, and Instagram and Foursquare only added permissions prompts after the Path flare-up.
:source: Source: Venturebeat.com