Whereas GNOME 3.0 is looming, I thought I would share these links from Vincent Untz at the GNOME foundation:
"We use GNOME Goals pages to track migration for this, and each page has some documentation on how to accomplish this.
"The most useful for the GNOME 3 effort are probably:
All the GTK+ work:
http://live.gnome.org/GnomeGoals/GDKtoCairo http://live.gnome.org/GnomeGoals/GTKRenderingCleanup http://live.gnome.org/GnomeGoals/GtkObjectRemoval
pygobect + introspection: