Collaborating with Google Docs
Posted by Michael Paskevicius | 2 Apr, 2009You can see who was the last two have worked on a document on the far right column. In this case Chodkinson was the last to edit the document today at 8:55am.

Once you viewing the document itself you can see what changes were made during the last edit. To do this you need to select File ---> Revision History. Changes are highlighted as shown below.

With help from:
www.brighthub.com/internet/google/articles/8236.aspx