When you double tap a video, you aren't watching it in pan&scan, its simply zoomed in on the middle of the video. Pan & scan is actually better than this, since they pan across the entire image to ensure that you always get the majority of the "action" in the 1.33:1 aspect ratio.
that is true, although my comment regarding pan and scan was meant to be broader than just the iPod/iPhone. I hate the fullscreen versions of movie releases vs. the widescreen version DVDs. The iphone does just zoom to change the aspect ratio from 16:9 or 2.35:1 to something else by cropping off the sides. Actually what is the aspect ratio of the zoomed in screen? I will have to pull out my ruler.