Sim, é obsoleto. Ele mudou no Xcode 4.3.
Agora tudo está na pasta Xcode.app.
A Apple falou sobre seu documento "O que há de novo no Xcode 4.3":
/Developer No Longer Exists
The simplification afforded by repackaging Xcode 4.3 as a single app bundle eliminates the need for the /Developer directory containing prior versions of Xcode. As a result, the Install Xcode application and the uninstall-devtools command line script are also no longer needed.
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