Google has had collaboration features for their productivity apps for a long time. So, in some respects, despite have the superior and more popular product, Microsoft is still playing catch-up.
Yesterday, Microsoft announced some updates to Office 365 which includes real time co-authoring features for the Office Web Apps.
Office Web Apps users can now share and edit files with other Microsoft Office users. In addition to providing the function online, documents can be edited offline and when reconnected to the Internet, the doc changes will sync automatically.
Read the full announcement which includes several other Office Web App updates: