Please! Try out hi.kg API.
It's implemented on json-rpc.
url: http://hi.kg/api.php
method: shorten
argument: url
return: shorten_url
Some examples:
<?php
require_once("jsonRPCClient.php");
$client = new jsonRPCClient("http://hi.kg/api.php");
echo $client->shorten( "http://www.osmonov.com");
?>
Also JSON-RPC PHP lib here
Have a nice shortening!