2 people in the german forum told me they have the same problem.
But i've tested installing MATE on a fresh standard installtion of fc16 in virtualbox. Here i can choose mate after instalation with 'groupinstall MATE-Desktop' in gdm (gdm-fallback).
Then i've installed gnome and gdm on my real system again.
Here i can also change the desktops in gdm.
Can you check if the mate-session file is installed?
[root@mother rave]# ls /usr/share/xsessions/
All Display Manager searching for session files in this directory.
Check if mate-session and mate-session-xsession is installed.
rpm -qa mate-session\*
And try a reinstall of those packages.
yum reinstall mate-session mate-session-xsession
Is something striking in /var/log/gdm/:0-greeter.log or /var/log/gdm/:0-slave.log.0 ?
If nothing works and you want to see MATE, create .xinitrc in your home directory witth this content.
exec ck-launch-session mate-session
Now you can start MATE with 'startx' from the console (runlevel3 or new multuser.target)
1. create the file
2. init 1 in a root terminal
3. init 3 in the single user modus
4. login with your user name