Looking at Yahoo Answers again two years after its launch, I think I was wrong to think of it as a question answering website.
Despite the name, Yahoo Answers is a discussion forum. People are using it like a newsgroup, chatting about various topics. They are not using Yahoo Answers as much to generate authoritative answers to questions.
For example, looking at the "popular" answers right now, I see these questions: "Rudy Giuliani vs. Hillary Clinton?" "What's the last CD that you started out LOVING, but you played it so much you 'retired' it indefinitely?" "Egypt: when did I feel sad in Egypt?" "Name 5 one hit wonders of the eighties?"
These are not questions that have any objective answer. Rather, they are a discussion started with a subject line in the form of a question. People are "answering" a question not to provide an answer, but to engage in a conversation and chat with other people.
If Yahoo Answers is a discussion forum, it has a few implications. First, it should be compared not with the now-defunct Google Answers or Google's NLP question answering work, but with Google Groups, Slashdot, and other popular forums.
Second, those seeking to emulate Yahoo Answers probably would be mistaken to focus on question answering over community. People using Yahoo Answers are seeking conversations, not truth. The site is successful because it creates fun discussions and entertains people, not because it yields knowledge.
Third, Yahoo Answers itself may want to emphasize features that favor discussion and deemphasize features focused on generating high quality answers. In particular, while the "best answer" feature creates a fun, winner-takes-all type of contest, ending the discussions after a short period of time may be undesirable if the discussion is still attracting attention. In addition, if promoting discussion is the goal, features that help people find discussions they want to join would be beneficial; search and browse features may want to favor that over finding direct answers to questions.
I have to admit, I am late to the party in understanding the true purpose of Yahoo Answers. Two years ago, when Yahoo Answers launched, Gary Price said, "Will Yahoo Answers simply be the next generation of an online bulletin board?" Looks like he was right on.
See also my Dec 2005 post, "Yahoo Answers and the wisdom of the crowd", where I, mistakenly it appears, focused on Yahoo Answers as a question answering tool.