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 first place to look is in the struts-examples-1.3.5.war file that comes with the Struts download. Unzip the file and look at the source code. You will find a working example of a file upload there.