Well I must admit to being somewhat taken aback here. This whole social networking thing is an Internet explosion of often highly interesting and/or voyeuristic content from millions (billions?) of everyday people like you and I. I thought the Facebook craze was amazing but in my opinion Twitter has taken everything to the next level with "What are you doing?" - LOL!
I never thought the day would come when you could literally jump into someone's back pocket (virtually ANYONE's) but it has come to pass. Is it scary? Hmmmm.... maybe a little, but it is also AMAZING by it's nature, offering updates of people's thoughts and activities though a web GUI or even more importantly (from a telecommunications standpoint) via your mobile phone.
People are literally offering up their thoughts on a myriad of topics (literally anything qualifies as content here!) and others around the world are connecting to and following that content on an on-going basis. Now you CAN control WHO follows your Twitter feed (if you wanted to create a private network) but what's the fun in that? Don't we all want to feel like we matter? Well at Twitter, you have a forum to become important (or at lease interesting) to as many people as you can attract via your "content".
It's a crazy world we live in... (and now I have to go buy a BlackBerry!) ;-)