The use of “shiftlogs” is one of the most interesting topics: “shiftlogs” are group weblogs that employees on each shift of a 24 hour work day use to communicate with each other. It sounds like they log events. It’s better than sending emails around.
Mayfield’s notes on internal wiki use at Disney (and his asides) are interesting as well, esp. in the area of carving out different workspaces for different sets of people/roles/responsibilities.