The release announcement with source download links to all of the packages can be found in this mailing list message. When scanning through the change-logs for the core and application components to GNOME 3.3.1, some of the items that stick out are listed below.
Empathy: Rewritten "New Call" and "New Conversation" dialogs. TThe experimental "Call UI" has also been improved.
GNOME Control Center: Various improvements to the many control center items.
GNOME Shell: The instant messaging state is restored when logging in, improved contact searching, improved application searching, context menus with cut/paste options for most entries, and various fixes.
GNOME Themes: A new standard wallpaper.
GTK+: New theming improvements and many bug fixes.
Mutter: Support for keyboard window switching during drag-and-drop. Plus various fixes.
Nautilus: The GNOME file manager now uses GtkGrid and no longersome of the deprecated parts of the GNOME API. There's also many crash fixes.
Glade: Optimized loading time.
Among other changes set for GNOME 3.4 are many improvements to the Evolution email client, finishing up the application menu, gnome-boxes as a GNOME application for accessing other computer systems/images using libvirt, enhancements to GNOME Documents, and network zones support in GNOME.
GNOME 3.3 development releases will continue through early next year, enter beta in February, hit the release candidate stage in early March, and hopefully be gold on the 28th of March.