What the (censored)?! I need to get the raw post data from a PHP script, and there's no documented way to do it. The usefulinc XML-RPC library uses $HTTP_RAW_POST_DATA, and if you search on the PHP site that variable was documented, but it's not anymore since they created the "superglobals" and reorganized the documentation.
Oh yeah, the main reason I'm upset is that I'm trying to use $HTTP_RAW_POST_DATA because that's what the XML-RPC library uses, but it's not working for me... aaaargh!!
Hey, it turns out that $HTTP_RAW_POST_DATA does work, it's just that it doesn't show up if the type of data you send is plain =application/x-www-form-urlencoded=, but it does show up if you use something like =text/xml= 
$HTTP_RAW_POST_DATA=isset($HTTP_RAW_POST_DATA)?$HTTP_RAW_POST_DATA:file_get_contents("php://input");