var lstGalery = [];
    function launchGalery(){
       lstGalery = document.getElementById('zoneDiv').getElementsByTagName('div');
        viewGalery(1);
        }

    function viewGalery(numDiv){
         if(numDiv==lstGalery.length) numDiv = 0;
         for(var i=0; i<lstGalery.length; i++) lstGalery[i].style.display = numDiv== i ? 'block' : 'none';
         numDiv++;
         setTimeout("viewGalery("+numDiv+")", 2000); //toutes les 2sec
        }

//window.onload = launchGalery;