I am guessing this would be a valuable addition to web browsers in the future. With this technique it is easy to target an image for viewing in multiple displays (e.g. a 4:3 screen or a 16:9 TV).
“Seam carving” allows an image to be resized non-uniformly, so you can change the height to width ratio in the image without cropping, but also without distorting important features in the image (such as faces).
The video shows some intresting results when using this method too much, but the overall result is very impressing.
Hackzine has more details.