"As for the Qt (not KDE) dual-licensing, it has for years been a bad bit of P.R. for Trolltech, until they finally gave in and released a GPL version of Qt4 for Windows last year, although it's still a bit cut-down (no XP styles, doesn't compile under VisualStudio etc.)"
This is a rather narrow view of events, and since KDE very much relies upon Qt, you cannot separate the two in licensing terms. Try this for starters:
What I fear, and what seems likely, due to the "fields of endeavour" bit mentioned above, is that the GPL will be incompatible with the Castle Shared Source license. This is going to create plenty of headaches.