But in many instances with social media, it seems to be a goal to have as many people as possible "follow" you or “friend” you, particularly if you are promoting a service, a product or, as I do, a blog.
And on LinkedIn, a social media site for professionals, the more connections you develop, the better able you are to network with other pros in your field, improving your chances of both enhancing your professional opportunities and helping others advance theirs.
Since social media is, in fact, networking, I do not believe simply "friending" a public figure or a source on Facebook is any more a breach of journalistic ethics than introducing yourself to and then keeping in contact with that public official using another platform (think phone calls or e-mail or even good, old-fashioned face-to-face meetings).
Simply because you've elected to "friend" or "follow" someone in no way means you have given them an open-ended endorsement or have become beholden to them.
In my opinion, the only difference in this situation would be if you are the type of person who is very selective about who you "friend" or follow on any social media. If you intend for your Facebook account to be exclusively for friends and family, then exclude public figures and sources. To do otherwise implies there is a level of intimacy that may cause some to infer the potential of an ethical breech.