Yes you could, I have always created a formula field to accomplish this as I tend to use this field in other areas of my applications and as a formula field it can not be changed unless you edit the original field. It is useful at times for example in one of my applications I have a case ID that HAS to be unique and I don't want anyone to be able to change this from a grid edit view so I display my formula field in my reports and the only one who could change the original Case ID is a Role with Admin or Manager permissions that can open the original record to edit it. I was assuming the original post was looking to do the same...
