I do not know who to do "autorun" with Gnome ( I just do not like it at all
), but in KDE to get applications to auto-run on log in you must look into your home directory. For example, in my case /home/ralvez/.kde/Autorun is the path to where I can put symbolic links to the applications I want to run.
Say I want to run "gkrellm" upon log in into KDE, then this is what I would do:
1. cd /home/ralvez/.kde/Autorun
2. ln -s gkrellm
And that's it. Next time you enter KDE gkrellm will start.
Other solution, as pointed very well by alienDog, is to restore the previous session, so whatever was "active" in that session will be active in the new one.
Hope this helps.