Adding image to link with CSS only

As seen in the video at http://sciencehack.com/videos/view/IDT2RMJNvSA#searchkeywords

The source code:

Very good explanation is in the video mentioned above. So far so good - unfortunately the technique, however cool it is, does seem to work in Firefox only. Or at least it does not work in the still most prevalent browser on the Net.

Here is how it renders (properly) in Firefox (tested with 1.5)

and here is how it looks in IE7: