I think the PERCEPTION (not necessarily the fact) of the difference between sinchronicity and asynchronicity is key here. Chat: synchronous. Mail: asynchronous.

I think the PERCEPTION (not necessarily the fact) of the difference between sinchronicity and asynchronicity is key here. Chat: synchronous. Mail: asynchronous. And then: real-time collaboration and edition is kind of orthogonal and very different (and difficult) to understand (very few times do you do something really collaborative, even on a blackboard).