Div that appears on rollover are more and more used.
It helps the user to not get lost and forgot what he was looking for by clicking and going to another page then to click again to go back to the initial page.
The user wins time (because div are already loaded on the page) and the user is more satisfy.
Examples : the difference between istock and gettyimages:
– in ISTOCK.com, when we are on rollover on an image a div opens and we can see the image bigger
– in GETTYIMAGES.com, we need to click on the small image to see the bigger image, then to wait that it uploads then go back to the previous page if we are looking for another image. We lost time.
They use the same process in AMAZONE or WORDPRESS, we can see the next step without clicking