Update: Due to user backlash, Facebook has suspended this feature for now. One reason is that, while it is opt-in to give this information to an app, you have to make that decision before you get to actually see what the app does, during the install process.

This weekend, Facebook updated its developer blog with some new abilities for developers of Facebook apps. The biggest change is the ability from those apps to now access user contact information like home addresses and phone numbers. This data used to be kept confidential from apps, but now they will be able to access it if a user grants that permission. There are some obvious uses for that, such as a shopping app which fetches your address for shipping purposes. Apps will have to explicitly ask for user permission, which will appear as a new entry on the Request for Permission screen, and they will be expected to follow Facebook's rules of conduct. The safest course of action, of course, is to not add your contact information to Facebook in the first place.