executing scripts at login and logout

[Martin (KDE)]

Hallo

is there a general way to execut scripts shortly after login (but 
before the GUI is started) and before logout (all GUI components are 
brought down)? For kde I can use /etc/kde/env and /etc/kde/shutdown 
folders, but what about other GUIs (like Gnome)?

I want to sync home directories from server to local host (if the 
server is available) at login and resync the data from local host to 
the server (if available as well).

Martin