Currently QtWebkit documentation is lacking info that you need to have networkservices capability when accessing network in Symbian devices. There is a generic mention of required capability on platform specific documentation http://doc.trolltech.com/4.6/platform-notes-symbian.html. My suggestion is to add networkservices capability when user does qt+=webkit in .pro file and document this in QtWebkit overview.
There is more generic task for this in Qt http://bugreports.qt.nokia.com/browse/QTBUG-14472 . Closing this as a invalid.