AutoAnswer has several uses like: baby-watching over FaceTime, auto-answering specific numbers while driving, while using your phone with a bluetooth headset, instant response to specific calls, untattented video conference (leave an iPhone in some place and call it via FaceTime, keep a constant connection etc) and the stealth mode which is an option that you can turn on/off.
AutoAnswer lets you choose numbers that you wish to auto-pickup and your phone will automatically answer the incoming call from those numbers, either instantly or after the amount of seconds you specify.
There is also a Stealth Mode, which you can use for remote surveillance, in which AutoAnswer hides the incoming call completely and the phone does not indicate that it has answered a call while you can monitor audio in the area.
The "stealth" call will not be written to call history and the phone will show no signs of a call (apart from the remote caller's audio which you can mute).
There is also a feature to hide the application from Settings. If you do hide it, the only way to access it is by opening Phone.app , dialing ***** (5 stars) and pressing the Call button. You can change this password in my preferences. If you forget the password, you need to type the first 5 digits of your Phone's IMEI in phone.app and press the call button. This will reset the password and all your settings. You can find your phone's IMEI by dialing: *#06#
You can purchase AutoAnswer from the Cydia Store for $1.99.