GNOME 3.9.4 brings with it now a Photos application that is similar to other desktop photo programs for managing local/online photos and offering other basic tasks for photo management.
The Clutter tool-kit for GNOME has improved state tracking and short circuiting, Wayland back-end improvements, and improved gesture recognizers. The Cogl OpenGL component also has EmScripten support, lots of Wayland back-end work and updated compositor support, a new fence API, improved blend state tracking, HSL color conversion APIs, and much more.
GTK+ 3.9.8 meanwhile has improved support for scaled output on high DPI screens but currently needs a Cairo branch for good support. This support is found in GTK's Wayland, OS X, and Windows back-ends.
More details on the GNOME 3.9.4 changes can be found via this mailing list announcement.