When I attempted to vote on my Firefox browser with the cookies for that site blocked, I got this message after I voted: In order to cast your vote please insert the letters that appear in the pictures above the pictures of the men. (I tried multiple times, entering the site new with each try, thinking maybe I'd gotten the letters wrong. You can't really mess up 'nqrt' can you?)
When I turned the cookies back on for that site, my vote went through fine and I got the 'thanks for voting' message above the pictures.
1st Conclusion: they know.
*cue spooky music* oooOOOOooeeeeEEEEEOOOOooooooo!!!!
2nd Conclusion: don't turn off your cookies, you won't be able to vote.
3rd Conclusion: Have a beantos... :beantos