Ages ago, I proposed that the best CMS for a company would be one which used e-mail as the front-end:
- all attachments are stripped out and stored on a server in an hierarchical structure based on sender/recipient/subject line
- all discussions are archived based on similar criteria, and can be reviewed EDIT: and edited like to a wiki
My one concern there would be edits: a CMS needs to support easily making edits to content (fixing typos etc) - editing existing posts via email sounds like it would be pretty fiddly.
The idea is content comes in via e-mail, stored in some sort of tagged structure, then edited like a wiki.