Here's a little bit of styling to make a text "Loading..." message (a la gmail).
Code:
	.loading-indicator {/* the selector used by YAHOO.ext.UpdateManager */
	    background: #3a6fb3; /* yui-ext blue background */
	    /* background: #7b0099; or y! purple */ 
	    color:white; 
	    padding:2px;
	    /* position in the top right hand corner of the containing element */
	    position:absolute;
	    top:0;
	    right:0;
	    width:auto;
	}