Based on this thread:
http://tech.groups.yahoo.com/group/ydn-javascript/message/34286

The idea is to have a convenience method for showing areas of focus.

The best axample I know of is in the extjs library, of which this method is demonstrated here in their "Getting Satarted" tutorial:
http://extjs.com/learn/Tutorial:Introduction_to_Ext

It would seem easy enough to tack a <div> on to the innerHTML of a given get("id") and follow it up by passing through an animation object to execute. As suggested in the thread, something like:

YAHOO.util.pulse("demo", anim);

And the guts, something like:

1. demo {

1. inner {

position: absolute;
height: 300px;
width: 300px;
top: 0;
left: 0;
background-color: red;
z-index: 0;
}

});
anim.animate();