Sample Call

<?php
// SOAP_CLIENT_BASEDIR - folder that contains the PHP Toolkit and your WSDL
// $USERNAME - variable that contains your Salesforce.com username (must be in the form of an email)
// $PASSWORD - variable that contains your Salesforce.com password

define("SOAP_CLIENT_BASEDIR", "../../soapclient");
require_once (SOAP_CLIENT_BASEDIR.'/SforcePartnerClient.php');
require_once (SOAP_CLIENT_BASEDIR.'/SforceHeaderOptions.php');

require_once ('../userAuth.php');

try {
  $mySforceConnection = new SforcePartnerClient();
  $mySoapClient = $mySforceConnection->createConnection(SOAP_CLIENT_BASEDIR.'/partner.wsdl.xml');
  $mylogin = $mySforceConnection->login($USERNAME, $PASSWORD);
  echo "***** Get Server Timestamp *****\n";
  $response = $mySforceConnection->getServerTimestamp();
  print_r($response);
} catch (Exception $e) {
  print_r($e);
}
?> 

Sample Output

***** Get Server Timestamp *****
stdClass Object
(
    [timestamp] => 2008-09-17T00:27:13.024Z
)