This also brings the iPod touch in line with most of what the iPhone has. Besides the cell service (obviously), the GPS, and the mute switch, the iPod touch really is, as even Steve commented at last week's event, "an iPhone without the contract."
Update: According to iFixit's teardown of the iPod touch, the component identified is actually a microphone and not a vibration motor. Mac Rumors points out that Apple has updated the iPod touch's FaceTime page to remove all reference to vibration. It appears vibration continues to be an iPhone-only feature for now.