Greg - sorry I didn't see this until now! I have a number of links for you, but I'll share my personal experience (This is from a Social Days blog post from 2007):
I've dabbled with Social Media for years. RSS feeds for news, a blog here (Blogger), or there (LiveJournal), started a MySpace that didn't really excite me, all - nice - but nothing really exciting. I loved learning new technologies, systems - but my real passion was testing productivity applications and services (much more fun than that looks written down here).
Then came
Twitter. I joined in Dec 2006 - don't remember how, although I blame/thank
Daring Fireball - and I was instantly hooked. Love at first
Tweet.
I wasn't completely faithful. I was one of the people that followed
Leo Laporte the night he left for (and broke!)
Jaiku. Then came
Pownce. I'm enjoying my Powncing and my friends there, but Twitter is still where I end up.
I also like the
Twitter crew. They use their own product, are smart, they work hard and seem to treat their employees (and
others) with respect. Not just because they
gave them all iPhones (although that didn't hurt). I wish them much success.
Twitter has opened me up to an entirely new sphere of influence. It has introduced me (not actually - in a stalker-kind of way) to developers, strategists, bloggers and personalities that I'd have not met (easily) elsewhere. Through these contacts and 'friends" (in the social networking sense) I have expanded my knowledge, made significant contacts, started two blogs, changed jobs, have been asked to speak on Social Media and also contribute to a book.
In a very real way,
Twitter changed my life.