SharePoint 2010 with all versions they released have a feature called co-Authoring. Co-Authoring is very useful feature when people with the same time working with the same document and do some update with the same time.
This feature only worked not for all Microsoft office stuff. Only working with Ms. Word, PowerPoint and One Note 2010.
So, how about Microsoft Excel 2010 ? Can we do co-authoring ?
The answer is “No”, you cant do co-authoring using Excel client App. But if you have a Office Web Apps installed on your SharePoint site, what you can do is edit via browser and your team as well then you and your team may do co-authoring.