Introduction to QObject on Informit.com
The QObject Class in Qt4: 9.1 QObject's Child Managment
Informit.com has published a chapter from Alan & Paul Ezust's book Introduction to Design Patterns in C++ with Qt 4 discussing the QObject class, the Qt class which handles signals and slots, parent-child object relationships and internationalisation and from which widget, layout and network connection classes are derived.