This was an interesting Thing. I don't deal directly with students, generally, so I am not employing Digital Citizenship lessons, but some issues I'd been wondering about personally were addressed.
One thing that has sat uncomfortable with me in the past several years is employers (and schools, it would seem) use of social media as a means of vetting or investigating potential employees. Yes, it is foolish to put anything terribly objectionable or offensive online; you should always be careful about what you put online. But more in the interest of being a good "digital citizen" than because you're afraid you won't get a job. This article addresses many of my concerns and I agree with its author that rather than strictly warning students to beware what they post online, we should be letting employers and schools know that this is an invasion of privacy and we are not ok with it. What is personal should remain so, but I'm firmly in favor of separating personal and business.
On a different note, the Digital Leadership Continuum chart by George Couros is a valuable piece of self-reflection for educators and administrators, with an emphasis on the latter. I think it's doing students a disservice to block all social media and not inform them of how to use such sites wisely, kindly, thoughtfully.
Lastly, I'd like to mention that I really appreciated the link to the article from Computer World about how to remove your personal information from data mining sites. When I do a Google search on myself, not much comes up at all. I have my Facebook profile fairly locked down and the fact that I use a nickname sometimes and my full name sometimes, helps, too. (And I wonder if the fact that my last name doesn't sound like it looks, to English-speakers, anyway, helps?) I plan to use the provided opt-out forms from the above linked article to remove the bits of information I did find on myself using the pipl search that was also listed in the Thing 15 resources.