True for Apple, untrue for DVD, which for 720x480 is a 3:2 "frame".
720 is higher resolution than 640, so, for Apple SD, there will still be the knock
against it that it is still "sub DVD" quality. Some hoped that Apple SD anamorphic
would be just an H.264 version of the MPEG-2 DVD bits at the same rez.
Perhaps the Broadcom decoder in the iPods are limited to downsampling
640-wide with PAR, or maybe this is a studio-imposed deal.
But for a dollar more, this all changes.