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.
Reverting to URL rewriting does NOT happen automatically. The servlet engine will automatically recognize session ID values that appear in URLs but it is up to the programmer to encode session ids in URLs that your servlet or JSP generates. Bill