I've been playing around with validator.nu the last few days. I have been trying to get a standalone version working so I could package it up and puppetize it. Unfortunately a lot of the standalone jar builders failed (java hell).
I finally found that it's been released here: https://github.com/validator/validator.github.io
I whipped up a basic rpm to use this and install an init script etc: https://github.com/NoodlesNZ/validator-nu-rpm