Advanced Chat for Collaborative Google Docs Editing
Google has introduced a new chat feature Discussions to Google Docs which allows multiple users to edit a single document simultaneously while having discussions. The new chat feature of Google Docs will be available in next few days for all users with personal Google Accounts as well as to Google Apps customers on the Rapid Release track.
How to Use Google Discussions
Go to Google Docs
Create a new document
Click at discussions
Write something and click post
Other will also be able to see this discussion about the document
Check out the intro video of Discussions feature in Google Docs.