An article here in http://ago.tanfa.co.uk/css/examples/css-dropdown-menus.html where I found the technique. I haven’t actually use it (maybe later) however I have a similar style in which I used in my portfolio. It’s a on hover mouse image preview, I like doing this css techqniques as it appears to be faster than using other javascript framework like mootools or jquery.

I will keep you inform if I have implemented this.