Also, after an experiment that automatically posted my Google Reader starred items to GroupMe via http://ifttt.com (awesome service), I've decided that SMS is the wrong way to share articles.
Totally depends on the article and expected audience. For me, Twitter is for articles that are startup/tech related. I work hard to maintain my public persona on Twitter and really filter what gets posted there. I syndicate everything from Twitter to Facebook. Facebook is for funny stuff my mom will like. Email is for specific clusters of folks that will find the article relevant, though I usually end up sending articles to the same 2-3 groups of people. My blog is a special case. I only post stories there that I think reflect my personality and deep interests.