On few of my sites running drupal and which had ALOT of bogus registrations and comments, all spam was stopped. So far it works. Different story once it get big enough to warrant specific implementation, but we are not there yet.
To be precise, right now it uses Dogecoin proof of work. I got it running pretty good with asm.js compiled scrypt miner code. In future I will need to solve scaling problem, as right now it runs with fixed 2 threads only. In future it will self adjust based on user computer performance.
Right now there is no payouts to webmasters, but this is next feature I am working on. It will be made directly to webmaster dogecoin address from p2pool I am running for this project.