Would someone with lesser rep or a less famous name have received the same number of votes/answers as Joel? I know the question was briefly closed, but it got reopened when the intent was made public. I think someone did try it, but I don't think their question was suitable for the experiment and it was soon closed.
Similarly, do answers by Jon Skeet and others with > 20K rep garner more votes than equally correct votes by others less notable? Is this because of their name, their rep, or the fact that the answer is correct? I would hope it's the latter, but perhaps we ought to find out.
I wonder if the following experiment would yield any useful information: If Jon created a second account under a pseudonym and posted a few answers along side slightly "worse" answers credited to Jon so we can see which ones garner the most votes.
Another experiment (though this would require a change to SO) could be to hide the identity of the poster for a period (a day?) but leave the (approximate) rep score visible. This might show whether people were using the rep as a guide. On a personal note, if there are two equally correct answers I tend to award my up-vote to the one with the lowest rep score - to spread "the love" around (so to speak).
I'm not saying that questions and answers should be permanently anonymous, or that there shouldn't be a way of finding out the identity of a poster straight away. I just feel that the question or answer should be judged on its own merits rather than the perceived merit of the poster.