The title attribute, title="Keywords">, are one of those topics that are debated in the SEO world. Some SEOs say it does have an impact on rankings, others say it does not. Fathom, a guest author here, posted a thread documenting this study. The threads name is Title Attribute Control Test, where he clearly details the control groups and hypothesis. The study is not done yet, but it should be done soon. So make sure to check out the thread for updated information on this topic.