There are two types of backlinks .. do-follow and no-follow links; almost every one believe that the do follow links are very important for SEO. However, when it comes to no-follow, some people believe that they are waste of time .. while others believe that they are very important as well but in a different way .. Google said ‘In general, we don’t follow them’ .. This might not apply for Yahoo for example
Twitter and other social media provide no-follow backlinks .. However, it is difficult to ignore the power of social media in our society .. for example, with social media you can get more traffic to your site than what you might get from the search engines ..
In addition, the links to your site should have a natural pattern which include both do & no follow links. So whether they will improve the search engine ranking or not you should not ignore their great values