is a great addition and in many ways "improvement" on a lot of collaborative writing tools out there, in particular Pirate Pad
Yes, there is google docs but WideWord makes it super simple and secure to edit a document together. Perfect for a class or groups within a class.
Whoever starts the document (the teacher), sends out an invitation by email to others. (They are fully private) There are two types: Participants (who can edit and change the document) or Readers (who can only view). There are lots of other features and the layout and functionality is intuitive and "smart" -- features like : note attachements, seeing changes, one button printing and duplication.
This is a great collaborative tool for a teacher of English - a great way to get students writing online. Collaborative writing is really useful for beginning and intermediate level students -- web 2.0 really makes this happen! If you are interested, you can even share "contracts" with students there. Draw them up together and sign. The perfect way to start the school year - signed contracts and goals!
Check out the WideWord I started for EFL Classroom 2.0.
Checking to see if you can link a document there!