This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
The request parameter name and values represent key-value pairs and hence I would imagine that it would be stored as a Map in the request object. And being a Map, there is no order guaranteed. Neither should it be of any consequence.