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.
Sorry, was thinking of a java.util.Date, which is what the formatDate tag works with. This will be a little more challenging. One approach I've used for one way formatting (i.e. command to JSP only) is to have a getStringDatetime() method that does the formatting on in the command class. If you need to also bind an entered value back to your DateTime, you'll need to use a property editor.