Thank you, thank you, thank you. It is always a pleasure to work with someone who knows their stuff.
I had overlooked the step of connecting FortuneServer's signal to Dialog's slot in the dialog.
I added in dialog.cpp:
connect(&server, SIGNAL(connectionMade(QString)), this, SLOT(setConnectionText(QString)) );
Once I put this in, it worked like a champ!
Marking it solved.