Well I was going to say I don't really see how this is much different from e.g. Google Groups. Groups messages go into an archive that is searchable/readable by new members. But just having a message archive isn't really that helpful unless it can be organized further, and that's where it breaks down -- the job of organizing the group archive has all the same problems of keeping the team wiki up to date: its easy to get behind, and the content grows stale or hard to use.