After discussing with Brad and Clinton:
-the namespace for the imported targets is now "Qt4::", tested with Makefiles, Visual Studio and XCode projects
-the imported targets are always created
-if QT_USE_IMPORTED_TARGETS is set to TRUE (it defaults to FALSE), the QT_QTFOO_LIBRARY variables are set to point to these imported
targets, otherwise the old behaviour is used.
-on OSX if Qt has been found as framework, disable QT_USE_IMPORTED_TARGETS, since cmake doesn't handle the framework directory as location of the library correctly

Alex