Same Exploit, Different Day
Again, why the hell do we need all this obnoxious dynamic capability in our browsers? The very concept of MouseOver and MouseClick events has only been used for evil in my experience. The first I saw of this was on eBay where sellers would take over the right click trying to prevent lusers from saving their images. It obviously doesn't work for anyone who knows how to use their PopupMenu key on the keyboard but it annoyed the hell out of me as someone who uses Right click Back to navigate pages. If someone wants to display some popup text the Hint attribute generally works quite well.
You MIGHT argue for some valid use of the click events (expanding tree views and such) but the MouseOvers are inherently wrong. There is an argument that when a user clicks on something they realize there is potential for code execution but simply hovering your mouse should always be safe. I remember teaching people to hover their mouse over links before clicking them to ensure the actual target matched the displayed text (This is key to not getting goatse'd on a lot of message boards).
It would be nice if the browser (or NoScript) provided a way to turn all these various events on/off with some granularity. Better yet just remove them from the browser entirely and force web sites to code their site properly.