Dev:SpringBoard

SpringBoard is the singleton class that manages the application.

Monitoring Orientation of Top App
Whenever the orientation of the top application may be changed, -[SpringBoard noteUIOrientationChanged:display:] will be called. Therefore, you can hook this method to be notified of this info. The orientation (as angle in degrees) can be received with -[SpringBoard UIOrientation].

Sending messages to SpringBoard
Because SpringBoard inherits UIApplication you can send messages like this: [[SpringBoard sharedApplication] aMethod]

Getting the top SBApplication
You can get a reference to the top SBApplication like so: [[SpringBoard sharedApplication] _accessibilityFrontMostApplication].