I remember at R+ Social, it was possible to change your display name.
I can't recall if it was possible to see the history of the display name ie track the changes in the display name in case you were wondering if it was actually a new user or somebody who changed their display name.
What about on this forum? It seems possible to change your display name, but are the changes visible for everybody to see?
I believe hungryghost already mentioned that issue and indicated it was not possible at the user level. He indicated he might be willing to take a look at individual requests on a time available basis.