In a recent interview with PSM, Phil Harrison (Vice Prez of Research & Development and Third Party Relations at Sony) explained the real workings of the PS2's controller. Contrary to popular belief, the controller won't detect how hard you are pressing the button. According to Harrison, "It's a very clever new serial design which allows it to register the velocity of the button press without changing the feel of the button."

So, in fact, the controller will measure the speed with which you hit the button rather than the amount of pressure you are putting on the button. Until now, PS2 followers (myself included) have erroneously believed that the controller would measure the pressure on the button. This will change a few things, such as the idea that a racing game could measure how hard you are pressing down the gas pedal button, and have the car speed up accordingly. Since the controller wouldn't be sensitive to the force on the button when you're holding it down, this idea wouldn't be possible. However, the buttons will still work well with sports and fighting games, since it allows you to hit the ball (or the opponent) harder or softer with only one button.

The serial, or analog, button design will be implemented on all the buttons except Start and Select on the Dual Shock 2 controller. These buttons reportedly have 256 distinct levels of sensitivity, opening up whole new worlds for game developers. You can imagine the effects that this sort of precision control will have on games of every genre, especially fighting and sports.