When upgrading from libiconv-1.11 to libiconv-1.11-r0.01 it deletes libiconv.2.dylib & libiconv.2.4.0.dylib from $PREFIX_PATH/usr/lib installing them only to $PREFIX_PATH/lib, breaking several executables. Instead of executing them, I get : "dyld: Library not loaded: $PREFIX_PATH/usr/lib/libiconv.2.dylib".
I suspect you have bootstrapped long ago. libiconv should only install libiconv.dylib in usr/lib. You either have to reemerge packages using libiconv, or rebootstrap your system.
Sorry, it was "my" fault. System hadn't cancelled previous version (1.11) from world, so portage tries every time to unmerge the older one and deletes all libiconv.*.dylib from usr/lib/.
Unmerging the previous one and reemerging the latest one fixed it.