MPFoldTransition is a set of classes to add folding-style transitions to iOS 5 projects.
This is a really amazing project. Making these fold and flip transitions is a ton of work and Mark Pospesel has made it dead simple.
You can easily transition views using different styles with one method call:
+ (void)transitionFromView:(UIView *)fromView toView:(UIView *)toView duration:(NSTimeInterval)duration style:(MPFoldStyle)style transitionAction:(MPTransitionAction)action completion:(void (^)(BOOL finished))completion;
There are versions for UIViewControllers as well.