This week's book giveaway is in the OCMJEA forum. We're giving away four copies of OCM Java EE 6 Enterprise Architect Exam Guide and have Paul Allen & Joseph Bambara on-line! See this thread for details.
You have two choices:
1) Put a string representing the array in the hidden field. (such as a comma separated value format).. If you go this route, you call request.getParameter() and parse it in Java.
2) Store each value of the array in a field like we do with multi select fields. If you go this route, you call request.getParameterValues().