from the Google documentation:

Google sends you the new-order-notification to inform you that it has started processing an order. The new-order-notification includes the order's shopping cart, shipping method, tax, shipping address, and various other information. Google sends this and all other notifications as raw POST data, not as name/value pairs. You need to reply to the notification with a notification-acknowledgment message via HTTP response. See New Order Notifications for a complete description.

That's what's confusing me. How can I access the raw Post data?