In the past few months, Facebook has opened up the Facebook platform to the multitudes who want to write applications for the social networking site. While many are interesting and even more are annoying, all of them raise privacy issues to one degree or another.
If you, your friends, or members of your network use any third-party applications developed using the Facebook Platform ("Platform Applications"), those Platform Applications may access and share certain information about you with others in accordance with your privacy settings. You may opt-out of any sharing of certain or all information through Platform Applications on the Privacy Settings page. In addition, third party developers who have created and operate Platform Applications ("Platform Developers"), may also have access to your personal information (excluding your contact information) if you permit Platform Applications to access your data. Before allowing any Platform Developer to make any Platform Application available to you, Facebook requires the Platform Developer to enter into an agreement which, among other things, requires them to respect your privacy settings and strictly limits their collection, use, and storage of your information. However, while we have undertaken contractual and technical steps to restrict possible misuse of such information by such Platform Developers, we of course cannot and do not guarantee that all Platform Developers will abide by such agreements. Please note that Facebook does not screen or approve Platform Developers and cannot control how such Platform Developers use any personal information that they may obtain in connection with Platform Applications. In addition, Platform Developers may require you to sign up to their own terms of service, privacy policies or other policies, which may give them additional rights or impose additional obligations on you, so please make sure to review these terms and policies carefully before using any Platform Application. You can report any suspected misuse of information through the Facebook Platform and we will investigate any such claim and take appropriate action against the Platform Developer up to and including terminating their participation in the Facebook Platform and/or other formal legal action.
I doubt that many people read the privacy policies for each app they load and this is potentially dangerous because of the significant amount of personal information that third parties have access to. Application developers also face some issues that need to be considered.
Take a read of IMPACT®: Third party FaceBook apps are giving rise to serious privacy & legal concerns for a few interesting thoughts on these issues.