Among the GTK+ 3.2 features already is the HTML5 Broadway back-end for rendering GTK+ applications to modern web browsers, various widget enhancements, a GtkLockButton widget with PolicyKit integration, and much more.
Integrating Gail is meant to bolster the tool-kit's accessibility support. The GNOME Accessibility Implementation Library implements the interfaces defined by the ATK project that up to this point lived in a separate module from GNOME's tool-kit.
Topping off this release besides integrating Gail is that there's been a re-design move with assorted improvements to GTK's file chooser. The new file chooser has more of am emphasis on recently dealt with files.
More information on this new GTK+ release in the road to GTK+ 3.2 / GNOME 3.2 can be found in the mailing list posting.