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.
I remember when I was trying to get my first validation project working, it seemed like enabling this was a big mystery. In the end, all I had to do was enable <mvc:annotation-driven> + all the things you said you did. I haven't looked but I suspect that this tag actually enables the validator bean you mentioned.