See:
http://blogs.testbit.eu/timj/2008/10/07/07102008-recent-interviews/ (page moved)
Two weeks ago, Bruce Byfield did an interview with me about Manju. The article is now up at linux.com and gives a general overview of the project scope: Manju Project Article.
There’s also been a German interview with Sven Herzberg and me some months back at the Berlin Hackfest, which covers some historical background around Gtk+, some technical bits, possible future directions and how it relates to GNOME. The German podcast of this is up at Chaosradio Express: GTK+ und GNOME Podcast (DE).