Ryan Petrich, a popular iOS developer, has released ContactPrivacy, a tweak that alerts you when applications try to access your address book.
Prompts when apps want access to your contacts database. Inspired by Path.
The tweak was created in response to Arun Thampi's discovery that Path uploads your entire address book to its servers without notifying you. An opt-in update to Path is coming soon to resolve the problem.
You can download ContactPrivacy from Ryan Petrich's Cydia Repository (http://rpetri.ch/repo).