I realize that iOS 7 is not out yet and should not be discussed but I could not find the answer to this question anywhere and iOS 7 comes out in a few days.
I submitted
It doesn't matter what you name the file as long as you hook it up correctly in Targets General Tab. You just click the Folder icon and select the file you want to use. The naming convention only really mattered because that was what was in the info.plist by default for a new project.
And the Targets General Tab realy just sets values in the app's info.plist
Note: I have a build setting ICON_SUFFIX = "Beta" so my beta release via TestFlight has a different bundle ID and Icon so it sits along side my app store version and doesn't over write it.