As Aaron mentions, the current state of affairs with regard to collaboration is very much email centric. However, email is terrible for collaboration. If you have never given this much thought, sit a moment and really think through what it means to try to manage a project, with file versioning, in email. When you do, you can see how easily email can snowball out of hand, with nobody on the team knowing what file or which piece of info is the current, latest version.
I know this from painful experience. I have and my firm has had to manage very large projects via email, because of the strong resistance at the client to any web-based applications. People have been adamant: "we use email for everything." Yikes. There are even project management applications that cater (pander?) to this attitude, like Wrike.
My own opinion is strongly against the use of email for any attempts at collaboration, as it is simply the wrong system, but this all reminds me of an anecdote.
A scientist working on animal behavior rigged a gorilla cage with a banana, hanging from a string at the top of the cage where it would not be reachable. He put a ladder in the cage, propped against the side. The gorillas would figure out how to use the ladder, and just when a gorilla would reach for the banana, the scientist would spray the gorillas with cold water. The result? Enraged gorillas. Enraged and hungry gorillas.
But that wasn't the point. While doing this experiment, the scientist would swap out a gorilla, and repeat. Grab-spray-enrage, grab-spray-enrage. Eventually, the experienced gorillas were preventing newcomer gorillas from going for the banana.
Peer pressure, at its finest. Like the gorillas, our habits become entrenched, and there's a lot of "that's the way we always do it" in corporations worldwide, especially when people introduce new systems to use. That includes wikis.
I think Mindtouch might sponsor some demos to decision-makers, to show how great their technology is, how it's easy to adopt, and why email is most definitely not The Answer (tm). I thank Aaron and company for leading the charge.