Facebook has introduced a sleek and easy way to preview a friend’s profile on mouse-over.On mouse-over is a javascript code that allows you to show an image when you pass your cursor over a link or image.
Just hover your mouse cursor over a friend’s name on the home page and you will be able to preview part of their profile including names, picture(slightly enlarged) and the mutual friends you share. For Fan pages you are able to preview the number of fans as well as how many of you friends like the page.