User-Agent:       Opera/9.00 (X11; Linux i686; U; en)
Build Identifier: xfdesktop-4.2.3-4.fc5

If xfce4-session is installed and you right click on the desktop and select "Quit" from the xfdesktop window menu, you are asked about saving your session and then logged out of Xfce. 

If xfce4-session is not installed and you right click on the desktop and select "Quit" from the xfdesktop window menu, xfdesktop quits, with no dialog or indication of what happened. All the other Xfce processes keep running, you just no longer have a xfdesktop running. 

Reproducible: Always

Steps to Reproduce:
1. Install xfdesktop and make sure xfce4-session is not installed. 
2. login
3. right click on desktop to get the xfdesktop menu. 
4. select "quit"


Actual Results:  
see that you aren't logged out, but that xfdesktop quits silently. 

Expected Results:  
you are logged out of Xfce

This looks similar to 
http://bugzilla.xfce.org/show_bug.cgi?id=192
which was fixed years ago.

More info on the users env and such at the redhat bugzilla link above. 

Note that selecting logout from the panel works fine. 
Also if you have xfce4-session installed (and why wouldn't you?) it works as expected. 
Also, It seems to work fine in 4.4b1 at least (ie the bug doesn't happen there).