Probá así:
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></title>
<script>
function enviarForms(){
if(document.forms.length>1){
var ifr='<iframe name="pp" width="1" height="1" style="visibility:hidden"></iframe>';
document.getElementsByTagName('body')[0].innerHTML+=ifr;
for(var i=0;i<document.forms.length-1;i++){
document.forms[i].target='pp';
document.forms[i].submit();
}
}
document.forms[document.forms.length-1].submit();
}
</script>
</head>
<body>
<form id="form1" name="form1" method="post" action="test.php">
</form>
<form id="form2" name="form2" method="post" action="http://www.yahoo.com">
</form><br />
<a href="javascript:enviarForms()">enviar</a>
</body>
</html>
enviar varios formularios a la vez 
27/07/2008, 06:59
