One of the shifts in behavior I think we'll see over the next few years is a de-emphasis on email in favor of technologies more appropriately suited for collaboration.
Email is a communication medium. Not a collaboration medium.
Email is also best for two-way communications. One-way communications -- newsletters, updates, news -- is better in RSS than email.
The problem is that many people are in bed with Outlook (or whatever email system they use). So they use a two-way communication medium for everything. This is not efficient over the long run.
If you're one of those guys who "lives in Outlook / Entourage / Eudora" even when you're trying to brainstorm, edit documents, or plan an event, it's time to bite the bullet (ie, the switching costs) and think about what kind of information should flow through an email application versus other applications.
The question is, what are those other applications that should be part of your virtual office infrastructure?
(Hat tip to John Kembel for sparking this idea)