Dark Side of social media?

A couple of nights back I was at the Chinwag 'Dark Side of Social Media' evening get-together.
Some interesting thoughts about identity, but some real dark paranoia about that pesky interweb, too.
It seems to me that pretty much every disadvantage you can think of for social media - including posing as multiple identities, posing as someone older/younger than yourself, cyberbullying etc etc - can be replicated by the good old letter with a postage stamp affixed. Who checks your identity when you pop it in the post? I appreciate there are rules and regs about what can be sent - but the highly private nature of things in the post means it's extremely hard to prosecute anyone other than the person receiving.
The digital world of social connection may well mean acceleration in sharing, but it also means its easier to trace the dodgy types (eg MySpace handing over details of paedophiles) and also means we have a generation of kids growing up more savvy than ever before - placing them in the best position ever to defend themselves/spot those who might prey upon them.
The nature of this constantly connected generation means they are always but a text or a twitter away from help, too.
Dark Side? Sorry... I think the force is with us.

An aside. The Chinwag model - sociable as it is - offers just a little too much broadcast time (from the panel) versus networked conversation.
Perhaps they should try speed group dating (by which I mean informally introducing groups of people for short periods, before reforming the groups over and over) and bringing in thinkers from outside the industry. Make the new media wall a little more permeable?