usually the 'non-commercial' license is applied on free (as in beer) software, it will be uncommon if you add this limitation on a nonfree product, while other free editions exists and without the limitation, kinda strange to me. (obviously WinPhone tools are free and can build commercial apps, if you add native sdk to WinPhone, then it'll get weird.)
GTK/Qt, good idea. GTK+ is not ready for Windows yet, but Qt has an existing official vs addin, and ms can please the Nokia guys, so why not. (ps, not conspiracy but actually I do remember some ms guys said their are considering options to support Nokia's other ecosystems, )
you can compile the code but you can't get the designer/wizards/debug extensions/etc working.