XCode 4: Archive is using old project name
The answer is fine, it's just not obvious on Xcode,
1) To edit your scheme, use Product -> Scheme -> Manage Schemes, once there, you will see the list, I know; there is no "edit" for the name as such, however, click on your scheme name twice (slow click), the name will allow you to edit it and change it.
2) To edit your Archive name (i.e. the name that appear under the scheme when you archive on Organiser), use Product -> Scheme -> Edit Scheme -> Goto Archive (left menu) -> and then enter what you like in the Archive Name.
I hope that help, the above answers are correct, just wanted to share the exact steps on how to edit, as I had one of those moments myself for not seeing an EDIT button there...
Regards
Heider