+3  A: 

No you cannot, unless there is a particular bug you have discovered. Is there any particular reason you think it is possible? This seems fairly easy to test, if you are worried about it. Just create two apps and try to access data from app A from app B.

Peter Recore
+3  A: 

No. But you could do it using remote_api (and with the permission of the other app's owner).

Nick Johnson