Large image links with new facebook interface.

How do we get larger image links than the small square ones we are used to on Facebook ? I see them popup a lot nowadays, just a link to a large image and therefore the preview of the link is also larger. I know it has something to do with the size of the image but my images are large and still I get the small preview link.cheers

push, i want it know too

image must by 400x210 minimum