Something strange is happening to the way I use email.
Last week I sent someone a long, information-packed email that they had been expecting. I immediately followed this up with a direct message on Twitter letting them know that I had just sent the email.
Later on that evening I received a reply on Twitter thanking me for the information. There was no email reply.
Look at this another way. I have three email accounts that I use regularly: my work account, the Engine Room's own account, and a personal account I've held for about a decade. I now check the last of these around once a week, down from every day a few years back.
If I want to send a quick, casual message, I'll use Twitter; if I want to share a link, I'll use Delicious; if I want to pose an open question to some work colleagues, I'll use Yammer; if it's work-related but not pressing, I'll use LinkedIn; and so on. Email's role is becoming much more niche.
And that's strange, because email is ubiquitous: pretty much everyone who has uses the internet has an email address. Not everyone uses Twitter, or Delicious, or Google Wave, or any of these other fun forms of communication.