There's always space for email. My private phone conversations might be useful and/or interesting to random people and somebody out there might have some helpful insight, but seriously... They're my <i>private</i> phone conversations.<p>Maybe I'm old school, but for me, there actually is something appealing about expressing a thought in more than 140 characters and specifically to a person of my choosing. I'm Web 1.0 like that.
Translation: Apples vs. Oranges. Fight!<p>foulmouthboy is right: There may be some overlap between these two communication mediums but they have two different purposes.
Email has it's share of problems, but it is a necessary tool. Businesses are utilizing Twitter and other media more and more, my office has only two people I can think of who aren't on twitter. It is used for inter-office communication etc.<p>However, email is the incumbent technology so it takes a major paradigm shift to unseat it. Something I haven't seen any new technology come close to.
I believe Twitter is a solution to the too much email issue, especially when they allow for groups. It forces people to get their point across in 140 characters. Why go on and on?