I have manually POST-ed your URL with an independent tool -
cREST client plugin for Chrome - and the result is the same "Array ( )", which means there is something wrong with your server configuration or PHP script.
Random ideas:
1) As far as I know the $_POST is deprecated in PHP. Perhaps try a more recent function?
2) Remember that with POST, parameters are sent in the HTTP request body, not in the URL (just in case this matters).
I am trying this with another host, and when i sent the information from a test page with a simple hidden object and a submit button, the post data transfered over. But when i try it with the chrome plugin or bitcoinnotify i get nothing. The PHPccode im using now is:
print $_REQUEST["type"];
?>
And this isnt my first PHP page either...im totally baffled on why this isnt working.