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.
There's no reason they can't exist side-by-side in the same application. There is also a Struts 1 plugin for Struts 2 that allows the use of S1 action classes, but it doesn't let us use S1 tags, so I'm not sure it's worth it.