I think it would be enough to put the score next to every share. It should be possible for everyone to recognize it's own shares. So you would publish the parameters for the algorithm (I know, you already did, but on the homepage or somewhere where it can be easily found) and how the miner can identify it's shares. I think that just hashing the workers user name would be anonymous enough.

With this information everyone can verify that every share got the right score and if the relation of his/her sum of scores and the payout conform. Actually, I never did that yet. But that's because I assumed that Meni himself checked this at Continuum.