If you were on Facebook over the past week, a friend of yours more than likely re-posted a message on your wall that said if you went into your "Account" settings and clicked on "Edit Friends" you would see all the phone numbers from your mobile phone Facebook is storing without your knowledge and making public. In response to the outrage, Facebook has made a statement denying that it is stealing your phonebook.
The problem stems from a feature found in the Facebook Mobile app called "Contacts" which syncs your phone's contact list with your profile. After it's synced, you can access all your numbers from your Facebook page where the numbers in your phonebook are then matched to people on your friends list. It looks shady until your realize the numbers came from your phone.
Facebook made a wall post yesterday attempting to reassure users who were concerned about their privacy:
If you would like to remove your mobile contacts from your Facebook page head to this page.