As a teacher, like it or not, at sometime you're going to have photos of you taken in class which will end up on Facebook /elsewhere on the Web.
This happened to me recently when a Tourism student of mine used her mobile phone to take a snapshot of me as I stood on a chair for comic effect (see left - thanks Sol for permission to use the photo). It was a surprise when I saw I'd been tagged, as I had no idea she'd taken the photograph, but I really don't mind it being shared here.
I think this is because I have got so used to living my online life in a very public way. I know it was difficult at first, and these questions of what I should and shouldn't share with people came up when I started blogging in 2003. I also have to say that, give or take a few minor feuds, nothing bad has yet happened to me sharing online (that I know about!). I have, though, heard some horror stories concerning other teachers and students and am sure that if any of this had happened to me I'd feel differently.
Another related blog post worth a read is the 'Concerned about Facebook? You're probably getting old'. Here, the author makes the point that privacy concerns are being voiced by people aged 35+ and wonders if it's because young people using these social networks are naive. I really don't think so - I think it's because new generations are growing up with this new idea of privacy (or lack of privacy) online.
Finally, the ability to easily reach other people using the web is creating a new kind of 'fame' (although 'fame' is the wrong word here - probably better to say many of us are now becoming 'not unknown') because of our web presence (we turn up on Google searches, etc). I am enjoying this and think it's related to Andy Warhol's idea of fifteen minutes of fame, when he said "In the future, everyone will be famous for fifteen minutes.".
I think Warhol's idea has changed. In the present day, it's more like 'everyone is famous in the eyes of fifteen people.'