Recently sources have been indicating that Leopard [the next version of OS X] will feature easy collaborative work throughout the OS.
The main idea is that it will be possible to declare a document as available for collaborative use over a network or Internet. Users who want to work on this document will be able to connect and work simultaneously on it. Modifications made by each user will be updated in real time for all connected users.
Sounds like SubEthaEdit. I’ve used SubEthaEdit with Rochelle and Catsy for writing papers and conference presentations. It would be great to have something that I could use with students across space and time.