Many GNOME packages have been updated for this 3.1.2 milestone. Some of the notable updates for this GNOME 3.2 development snapshot include a new Clutter release where COGL has been moved out-of-tree, Empathy has a new log viewer and supports CSS variants in Adium themes, a new experimental call channel handler for Empathy, improved SVG decoding with Eye of GNOME, GDM improvements, GNOME Shell enhancements, and much more. There's also GTK+3 tool-kit improvements.
The full list of GNOME 3.1.2 changes / translation updates / bug-fixes for the core modules can be found in this news file. There's also this GNOME 3.1.2 e-mail announcement.