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
Related to this - take care when manually merging strings into Localizable.strings - I managed to copy/paste BOTH strings from a NSLocalizedString() macro, so that the Localizable.strings entry was in this form:
"KEY" = "STRING", @"COMMENT STRING COPIED ACROSS ALSO, IN ERROR";
The bit ,@"xxx" on building caused me to get the error:
Read failed: The data couldn't be read because it isn't in the correct format.
In this case doing a quick search on @" helped identify the places I'd done this.