Description of problem:
Per the discussion on fedora-extras-list, Xsession entries should be only
world-readable, and not executable. gnome-session includes
/usr/share/xsessions/gnome.desktop set with 755 permissions, but it should be 644.
Version-Release number of selected component (if applicable):
With gnome-session-2.16.0-3.fc6, this is still executable and should not be.
Will be fixed in tomorrow's rawhide.
I can do updates for fc6 (and fc5, I guess) if you want, too. Just let me know.