Sharepoint Co-Authoring and Office 2007

I had a question about Co-Authoring that doesn't appear to be answered on Microsofts info page.

http://office.microsoft.com/en-us/sharepoint-server-help/document-collaboration-and-co-authoring-HA101812148.aspx

Are you able to Co-Author if you have all Office 2007 environment or is this only a feature with Office 2007?