Java is a very good option.
i had made this GUI in Java last year,using rxtx libraries for serial support.
But somehow my code was limited to win xp and below.
it didnt work in vista and in linux found it very difficult to install libraries and do stuff.
moreover it consumed about 220MB RAM.
This time i seek a speedier,more general,cross platform solution.I have no idea about wxWindows
I have also just started with GTK+ after rejecting QT.
Happy to hear that someone is interested in the project and has time.Hope to hear more from you.