Saw these callouts in a BusinessWeek article. Thought they were cool in providing a second layer of information. I thought it was counterintuitive that you had to click on the i-icon to close the box. It took me about a couple of minutes to figure it out. Also, there should be a way to turn of the highlighted information for people who like to read clean copy (i.e. Yellow is such a striking color). I can see this used in Wikipedia.