Funkar ej?

gistfile1.js

    window.addEvent('domready',function() {
      /* settings */
      var showDuration = 1000;
      var container = $('slideshow-container');
      var divs = container.getElements('div');
      var currentIndex = 0;
      var interval;
      /* opacity and fade */
      divs.each(function(div,i){ 
        if(i > 0) {
        div.set('opacity',0);
        }
      });
      /* worker */
      var show = function() {
        divs[currentIndex].fade('out');
        divs[currentIndex = currentIndex < divs.length - 1 ? currentIndex+1 : 0].fade('in');
      };
       /* start once the page is finished loading */
       window.addEvent('load',function(){
         interval = show.periodical(showDuration);
       });
     });


/* HTML
<div id="slideshow-container">
  <div id="slide">Hej</div>
  <div id="slide">Hello</div>
  <div id="slide">Tja</div>
  <div id="slide">Ho</div>
</div>
*/

/*
#slideshow-container { width:512px; height:384px; position:relative; }
#slideshow-container div { display:block; position:absolute; top:0; left:0; z-index:1; }
*/