Most evidence points suggests that it does. Canonicalization enables the search engine to see only one version of your URL. In all reality there may be several versions: http://yourdomain.com http://www.yourdomain.com yourdomain.com/ So you probably have links pointing from other web sites to your web site. If they are all pointing at different versions of the URL [...]

Continue reading about URL Canonicalization-Does it improve SEO?