This is a good start for something that should be native to WP. Instead of editing the HTML, there has to be a more elegant way to implement this. I would like to see a roll-over panel where you define your roll over actions and from there you get a short-code or something similar.
This is the code to get started, but the transition is really jerky.
<img class="mouseover" noresize src="image1.jpg" oversrc="image2.jpg" />
The noresize option doesn't seem to be working for me. Any suggestions?