When you use the Find Friends or Invite Friends feature on Facebook, it stores your imported contact data in order to generate friend suggestions for you & others. This is a pretty nifty feature, however some people might think that it invades their privacy.
With the Imported Contact Analysis Feature, we bring the same feature to JomSocial & CB with our People Suggest Extension. If you chose to use this feature, we recommend that you let your users know that you are doing this. Note that you need to be using Invitex as your viral invitations system in order to use this. In Invitex, you will find an option to "Store Imported Contact information for People Suggest". Switch that on to use this feature in People suggest.