I have finally upgraded from F13 to F16, using the pre-upgrade route but after spending yesterday trying to get Gnome 3.2 to work in other than fallback mode, I am getting rather frustrated.
There have been other posts of this nature but their suggestions have not worked for me.
The crucial point is:-
Dec 16 15:08:29 linux64 gnome-session: DEBUG(+): fill: *** Launching helper 'bash -c 'gnome-shell --help | grep -q gdm-mode && /usr/libexec/gnome-session-check-accelerated'' to know if session is runnable
Dec 16 15:08:29 linux64 gnome-session: WARNING: Session 'gdm-shell' runnable check failed: Exited with code 1
But, running the Live CD, Gnome 3 works without problem so the graphics card must be capable.
I am running the proprietary nVidia drivers rather than nouveau, they have always been better for me.
SELinux is disabled.
I usually run twin screens, so I reverted to single screen since that is how the Live CD runs.
I have applied the latest updates and am running kernel-3.1.5-2 with 290.10-1 nVidia drivers.
Output from "rpm -qa *\nvidia\* *\kernel\*|sort;uname -r;lsmod |grep -e nvidia -e nouveau;cat /etc/X11/xorg.conf" attached.