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.
Download the JWSDP from Sun. You'll find a tool called "xjc". There is an Ant task, which I know works, and I think also a command-line version which I haven't used. The JAXB documentation tells you everything you need to know about using xjc.