you can simply drag and drop and resort them with the mouse in the storyboard. it still works in 4.5.1
EDIT
maybe you have first to switch the storyboard view to "Source Code" and go back before you can drag. right-click the storyboard file and select "Open as" -> "Source Code" and then back again "Open as" -> "Interface Builder - iOS Storyboard". that should do the trick.
EDIT
Does not work in Xcode 4.5.2 anymore for me!
EDIT
In Xcode 5 preview 5 it works again. Seems that Apple did fix this bug in the new verion
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