Wow, that was an awesome article!
I have been thinking about the same problem for a little while, and have some comments on some of the stuff he proposed.
It doesn't surprise me at all that Salganik's experiment showed that popular songs would become more popular, almost regardless of their quality. This seems to be a hard-wired human character trait, to conform to popular opinion, even if contradicts direct observation (see the Asch conformity experiments or the No soap, radio jokes). I think that any "solution" to this problem is likely to be fighting a losing battle against peer pressure, since people will likely try to subvert the "find the merit" process in order to figure out what the group thinks.
On the topic of solving the problem of pre-existing bias, I say, "why bother?" He proposes a number of increasingly complex (though well-thought-out) solutions to the "Pro-Bush, Anti-Bush" article problem, all of which, I think, would be doomed to failure. This seems to be a cat-and-mouse game of "outsmart the rater" which I think the creator of the system would lose. If you try to make a smarter process of preventing people from injecting their bias into an article, they will just figure out a way around it. Rather than trying to outsmart the reader, simply include their bias in the rating of the article.
If you saw an article with a rating that said "95% of Bush supporters liked this article," it would tell you something about it, as would "90% of Kerry supporters also liked this article." You could rely on self-reporting or fancy statistical extraction of preferences to figure out who is a "Bush supporter" and who is a "Kerry supporter." That way, you wouldn't have to trick people into anything.
Additionally, who says something is an important part of what is being said. If you see an article about how 9/11 was a conspiracy by a well-known Truther, that is a very different piece of information than if President Bush says it. Likewise, a heavy metal fanatic liking a heavy metal song sends a different message than someone who thinks Vivaldi is just a young upstart and a passing fad liking the same song.
There could be problems with this (like how to keep the display of who said what short enough to be comprehensible), but it could be a step in the right direction, or at least something interesting to think about.