Leo Babauta of Zen Habits fame has ditched email and will primarily use Twitter:
… the people I communicate with the most are (mostly) on Twitter. What I love about Twitter is that it’s very limited (140 characters), so you have to keep things brief, and also there isn’t the expectation that you’ll respond to every message, as there is in email. Friends can DM me on Twitter for personal communication.
I find the using Twitter part more significant than the giving up email part.
Over the past year, I’ve observed that I’ve stayed in touch with friends and contacts from my undergrad and postgrad days (and former colleagues) who are on Twitter. I’ve found that I communicate at least once with everyone about once a week. Those who aren’t on Twitter have more or less fallen out of touch.
Twitter is definitely the best reflection of our expanding social networks and shortening attention spans. Telephone conversations lasted 15+ minutes. Reading and responding to an email takes perhaps 5 minutes; a tweet (or Facebook Wall post) takes seconds.
Finally, having these channels of communication has let us grade our social network according to closeness – I still call up my closest friends occasionally – those calls last upwards of an hour. I write to a slightly larger set of people with “what’s up lately” emails, and maintain a level of ambient Twitter-fed awareness of an even larger set.