Depending on what type of files you are working on… but for controllers and blocks you can use the preferred method of getting the vars out of the http request object…
$params = $this->getRequest()->getParams();
$myParam = $this->getRequest()->getParam('my_param');
otherwise the following should work from anywhere:
$params = Mage::app()->getRequest()->getParams();
I haven’t tried getting the raw POST vars, maybe Magento is resetting them in the request, but if it isn’t working for you try the above.
EDIT: Just realized you are using this in a CMS page… the above may or may not be of any use to you.