the ipad case is not material unless its made of lead, I suppose.
http://www.tsa.gov/blog/2010/04/trav...books-and.html
Electronic items smaller than the standard sized laptop should not need to be removed from your bag or their cases. It’s that simple.
But that won't stop them from giving your bag secondary screening. Even with removing my ultraportable, I think I'm about 50/50 or less on them going through my carry-on, removing some thing, and putting the entire mess back through one or two more times.
Ayyway, your ipad, kindle, netbook, etc can stay in your bag. Case or no case.
-David