$filename = dirname(__FILE__) . '/image.jpg';
 
$postData = array(
    'fileupload' => '@' . $filename,
    'key'        => '*********', // ключ полученный на странице http://stream.imageshack.us/xmlapi/
    'xml'        => 'yes',
);
 
$ch = curl_init('http://www.imageshack.us/upload_api.php');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, $postData);
$result = curl_exec($ch);
curl_close($ch);
 
$xml = simplexml_load_string($result);
 
if (!$xml)
{
    echo 'Error';
}
else if (isset($xml->error))
{
    echo 'Error: ' . $xml->error;
}
else
{
    echo 'Image URL: ' . $xml->links->image_link;
}