New Login Screen
The GDM login screen has a facelift in Fedora 16, matching the GNOME 3 look & feel. There are some pretty slick animations you'll notice while interacting with it as well.
New File Previewer
The Nautilus file manager has a new file previewer called 'sushi.' You can try it out by selecting a file in Nautilus and hitting spacebar to activate the preview. Here it is previewing a photo.
Color Management
GNOME color manager has been integrated with the GNOME Control Center. It allows you to calibrate your displays using hardware calibration devices (Such as the Pantone® Huey™) and it also allows you to calibrate cameras and printers using a variety of color swatch cards.