tedster - 12:38 am on Jan 24, 2011 (gmt 0)
Yes, it's a hard job to use algorithms to assess quality - but I don't rule it out. For example, there are linguistic algorithms today that do a pretty good job at determining the gender of the author!
Now that Matt Cutts has given us the phrase "document classifier" in this context, I think that's a clue at what direction they'll be testing. So a forum thread would be held to a different measure than a blog post or a product description.