The new gdm uses a new common session format. To make gdm pick up KDE for its list of session kde needs top put a /etc/X11/dm/Sessions/KDE.desktop file (note the 'dm' is not 'gdm'), similar to the gnome.desktop one. The Exec= line in there is the argument passed to Xsession.
could you please give more infos about the syntax of desktop file? thanks
The .desktop file is pretty much like the desktop files from www.freedesktop.org. Except only a subset of the functionality is used, for example icons are not yet used, and TryExec is not implemented yet either. The Exec= line can additionally be 'default' (runs system default) 'custom' (runs ~/.xsession) or 'failsafe' (run a failsafe xterm). In the rh Xsession, custom and default would really be the same since by default we run a custom like session. KDM will at some point support the same setup.
Created attachment 94061 [details] The session desktop file used for gnome. I haven't managed to build the new gdm just yet, so here I'm attaching how the gnome session desktop file looks. I hope to get the new gdm built today.
it's fixed in kdebase-3.1.3-7.