As many people know with the 3.0, that holding down the home button will not force quit the application. What most people don't know is that there is a new way.
Press and hold the Sleep/Wake button on top of iPhone for a few seconds until a red slider appears, and then press and hold the Home button until the application quits.
Press and hold the Sleep/Wake button on top of iPhone for a few seconds until a red slider appears, and then press and hold the Home button until the application quits.