Having had the nano for a few weeks, I think it was a major design flaw to put the headphones on the bottom.
Not only does it put the screen where your change is, but have you tried running with it? With the cord coming out the bottom, it goes toward your body instead of away from it, and this minor difference makes it a lot easier for the headphones to get caught up as you move.
Whoever said it makes more sense because you pull it out of your shirt pocket--I can see the sense in that, but honestly it's just as easy to pull it out of a shirt pocket right-side up.
They perhaps should have switched to the smaller-style mini-plug like cell phones have, if space was the issue.
Bob