In the gallery, thumbnails are arranged on the left screen, with a bigger view on the right. Drag a thumbnail across to the other screen and you can upload it straight to Facebook, or e-mail it to a pal.
You can set video to play on both displays at the same time. That won't come in handy very often, but could save your bacon if you're sat opposite a friend on the train, for example. The Medias W N-05E is coming to Japan in April -- fingers crossed it arrives in other countries, too.