In xcode4, (I have used v4.0.1 until now and downloaded v4.0.2 yesterday.) I made Localizable.string files and compiled my project. (As you know, my source code uses NSLocal
Per Apple:
If you run into problems during testing and find that the functions and macros for retrieving strings are always returning the same key (as opposed to the translated value), run the /usr/bin/plutil tool on your strings file. A strings file is essentially a property-list file formatted in a special way. Running plutil with the -lint option can uncover hidden characters or other errors that are preventing strings from being retrieved correctly.
Fire up a console window, go into your project folder, and do:
/usr/bin/plutil -lint ja.lproj/Localizable.strings
(obviously replace the correct language folder name). This will tell you exactly where the problem is!