The Problem is that /etc/gdm/Sessions/* aren't read anymore, from now on sessionfiles should go into /etc/dm/Sessions/ (but as far as I can see part of them go into /usr/share/xsessions/. At least gnome.desktop did) So you'll have to wait untill all Packages, providing some sessionfile, got updated to use the new path and the new fileformat (*.desktop).
I read that it is possible to use the kdm sessionfiles in gdm but I can't remember where I read that. I believe it was some Debian bug report filed on gdm but as I said I'm not quite sure. Part of /usr/share/doc/gdm/changelog.Debian.gz: <snip> * With the new Xsession.in that uses the Xsession.d dir to start up, and the /etc/dm/Sessions dir supported by kdm and gdm for programs to indicate they should be on the session list, all that's needed is those programs to supply desktop files for /etc/dm/Sessions (closes: #84396) </snip> You could also have a look on some of the bug reports http://bugs.debian.org/cgi-bin/pkgreport.cgi?which=pkg&data=gdm&archive=no At least some of them helped me. MfG Marcel
