Yes, this. In a corporate setup, you need a messaging system that, for lack of a better description, is like email but persists like a message board. Targeted to a particular user/users but available for the next person to join the team without someone digging through their mail looking for the message.

The problems with adoption of current solutions (wikis, hosted stuff like Basecamp) are that many corporations don't let you host proprietary data offsite, and adding another server is something that is so difficult as to be essentially impossible. Not to mention "another server" could be one of 50 alternatives, all incompatible.

There still will adoption issues, as it doesn't seem like Google is aggressive in pursuing business customers, and I don't know if they have good answers for the questions that will come up. But I see Wave as essentially a protocol designed to solve the same sorts of problems as Basecamp et. al.