cargue el jquery al head y tampoco funciona:
Código HTML:
<script type="text/javascript" src="jquery-1.3.2.js"></script>
asi:
Código HTML:
<!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=utf-8" />
<title>Documento sin título</title>
<script type="text/javascript" src="jquery.corners.js"></script>
<script type="text/javascript" src="jquery-1.3.2.js"></script>
</head>
<body>
<div style="background-color:#acc; padding:10px" class="rounded {10px}">
class="rounded {10px}"
</div>
<script>$(document).ready( function(){
$('.rounded').corners("4px");
});</script></div>
</body>
</html>