Interesting Factoid: Sites with Twitter Share button = 7x more link mentions than other sites
 

According to a report by Bright Edge, sites with twitter buttons have 7x more link mentions than sites without such buttons. See http://www.brightedge.com/socialshare

Hmmmmmm..... Is this a case of self-selection? Someone who put in the effort to put such buttons on their site would already be the type of person who'd be more gung ho about linkbuilding?

That, combined with the fact that they probably have other buttons that directly contribute to links (diggs, reddits, etc) probably help bolster their link profile. But yeah, people who use the Twitter button on their sites are just more likely to be savvy to basic SEO practices and will put more thought into link building.