I'm having a strange problem...
based on the example "Hackbook" provided by Facebook to demonstrate the proper use of the Facebook iOS SDK, I'm trying to implement the same thing in my app.
The wired thing is: Jumping back to my app works only when using Safari to authenticate. When I use the Facebook app, it doesn't jump back to my App, but curiously to the still existent "Hackbook" app on my iPhone.
Authenticating via Safari works just fine on both device and simulator.
Any ideas?
Are you using your own App ID in your app's plist for the FacebookID property and the URL scheme?
If both apps register the same URL (both have the same app ID and are installed on the same device at once), it may just be a coincidence that one returns back to the other app in one instance and your app in another instance.