It should be noted that $HTTP_RAW_POST_DATA only exists if the encoding type of the data is -not- the default of application/x-www.form-urlencoded, and so, to accessing raw post data from an HTTP form requires setting enctype= in your HTML.
$GLOBALS["HTTP_RAW_POST_DATA"] contains the raw POSTed data from a request. Also available (obviously) as $HTTP_RAW_POST_DATA in the global scope. Thanks to Manuel Lemos' SOAP server class for shedding some light on the subject. Apres, a toi de voir quelles conclusions en tirer, lol.