he serialized data are the values of the public properties of the object.
There is such a thing, as its exactly what designer is doing - ui files are XML representation of forms, so its even more detailed then just having a bunch of QObjects, but QWidgets and how they relate to each other in the GUI.
Have a look at the QtDesigner module, and specifically at QFormBuilder.
http://doc.trolltech.com/4.7/qtdesigner.html