Gnome development is starting to see some interesting changes. The first is the previously mentioned gtkbuilder support in GTK+ 2.12. This adds new features over the previous libglade implementation and also is now part of GTK+ so it can be used everywhere GTK+ is used.
Another ongoing development is GVFS. Currently gnome uses something called gnome-vfs which is great but is showing its age when it comes to newer functionality such as FUSE.
These new features alongside the amazing existing language bindings for GTK+/Gnome make for a very exciting time for Gnome.
Related:
Initial plans to replace gnome-vfs
GVFS announcement
Upcoming talk on GVFS at GUADEC
GVFS Benchmarking Ideas