I've seen this used, and Likno is apparently going to implement it with their "Tab Top" MLR script.

An MLR that can be set to automatically cycle through the regions, like a slide-show, would be a spiffy thing to spruce up a site. Often when I use an MLR, I wonder if any site visitors actually click through any of the tabs, of if they even know to. If an MLR cycled through each tab, it would make it more obvious -- and exciting, no?

Here's an example of the effect I'm referring to.