I have the sixaxis app, I think it was like $.99. If your device is rooted, you can get your BT mac address from your PS3 controller and pair it with a little help from your computer and a free program they offer. It takes about five minutes. I have my Nexus 7 and a rooCase which props it up horizontally or vertically and the controller works great. I don't see how anyone can play any emulators or FPS games with the on screen controls.
I didn't even have to root my Asus Transformer (TF101) to connect my dualshock 3. I just plugged it into the usb port (of the dock) and hit the PS button and it paired up when I disconnected the usb cable. Didn't work that way before ICS though. I love the idea of hooking up a screen to the dualshock!