A company called Tapster makes robots that can test out mobile phones before they go to production. Here's the $750 Tapster robot, designed by Jason Huggins. It allows you to test out interactions on real mobile devices by simulating a human finger on a touchscreen.
Here's an earlier version of Tapster, called "Bitbeambot," playing Angry Birds on an iPad. It's made from an open source 3D-printable Lego-Technic compatible building toy called bitbeam, and was originally created to play Angry Birds.