Here is the blog about it. http://googleblog.blogspot.com/2006/11/adieu-to-google-answers.html The blog mentions that there were over 800 people over the +4 years that participated in it. I would shut it down too if there were only 800 people.
Win some lose some. Google does have a thousand and one different projects on the go. They can afford to experiment.
800 people, can't believe that. How did that happen? This is the first I've ever heard google answers. I guess that's why. Yahoo answers did a lot of marketing.