According to a forum, Yahoo answers has “no follow tag” attributed to each link. It can be a good source of traffic to your site but won’t help you achieve search engine rankings.
http://forums.seochat.com/yahoo-search-optimization-60/how-can-i-create-backlinks-from-yahoo-answers-280221.html
Traditional SEO has centered around moving one web site higher in the search results. The latest forms of SEO such as SEO Monopoly center on moving multiple sites higher in the search results.
