With Twitter's recent SEO tweak to the profile title tag a lot of users are becoming aware that their Twitter profile is starting to rank #1 for their own name. Now this can have implications for those who have a personal blog and have built up their personal reputation. Instead of funneling visitors to your blog (that may have ranked #1 for your name) there is more of a likelihood that those visitors are now going to your Twitter profile instead. Getting bumped from #1 to #2 can result in 3.5 x less clicks and from #2 to #3 1.4x less clicks (source).
You may also want to add the rel="me" attribute to all of the links pointing to your personal blog. This can create a "bi-directional" link, proving that you have ownership of the web site. Watch Google's "Introduction to the Social Graph API" to see how rel="me" links work. I have not seen any studies that the rel="me" has any influence in search rankings. Not all search engines have adopted this format as well.