A ver si te sirve de orientación:
Código PHP:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<title>Documento sin título</title>
<style>
div{position:absolute;}
</style>
<script>
function verOrden(){
var els=document.getElementById('f1').getElementsByTagName('div');
var orden=[];
var divs=[];
for(var i=0,l=els.length;i<l;i++){
orden.push(parseInt(els[i].style.top));
}
orden=orden.sort(function(a,b){return a-b;});
for(var ii=0,ll=orden.length;ii<ll;ii++){
for(i=0,l=els.length;i<l;i++){
if(parseInt(els[i].style.top)!==orden[ii])continue;
divs.push(els[i].id);
}
}
return divs;
}
</script>
</head>
<body><form id="f1">
<div id="movible2" style="top:0"><input value="hola"/></div>
<div id="movible4" style="top:90px"><input value="va"/></div>
<div id="movible3" style="top:30px"><input value="como"/></div>
<div id="movible1" style="top:60px"><input value="te"/></div>
<br />
<br />
<br />
<br />
<br />
<br />
<input type="button" name="Submit" value="Orden?" onclick="alert(verOrden())" />
</form>
</body>
</html>