Facebook recently released their api 2.0 interface. With it came a variety of changes and new challenges. For example I you want more than basic information permissions then you need to show facebook what you will be doing with those permissions and ask for approval. User dis will no longer be the users actual facebook id. In fact unless you have multiple apps under the same company , one user will have a different id for every app. The current plugin expires early next year when 2.0 becomes required.
There are some cool features like you can create app specific groups and many other features. So if you want to group game users together(alliances.......) then facebook will handle it for you. Fun times
If you get stumped feel free to message me. I might be able to point you in the right direction.