This week's book giveaway is in the General Computing forum. We're giving away four copies of Arduino in Action and have Martin Evans, Joshua Noble, and Jordan Hochenbaum on-line! See this thread for details.
You need to provide more information. The portion of the build.xml you posted does not contain all of the information about the error. Please post the full build.xml and the full output from running ant. I suspect that your catalina-ant-classpath setting is incorrect.