Email, Dorsey explained, '[is] not great for communication because it's not focused on the most important thing. The subject is the message, and that's the message. The subject is in the message in the IM. It's bringing the content to you right away.Sometimes the subject is not the most important thing - except maybe when it has NSFW in it - but subjects like "Talking Points for Today's Meeting" don't communicate the important stuff and I'd really hate to get that info in via IM.
I'm still amazed by the denizens of Web 2.0's urge to kill e-mail. Why? It makes no sense. All information and communication is not meant to be broadcast and shared with the world (this blog post is not one of those cases). Even IM is directed to specific individuals and tends to be pretty private. So why can't we have it all?
Twitter Co-Founder Jack Dorsey On The Power Of Tweets