On openSUSE 12.1, I try to automatically start krb5ticketwatcher at the start of each Xfce session by having once executed
$ ln -s /usr/share/applications/krb5-ticket-watcher.desktop ~/.config/autostart/
such that "krb5ticketwatcher -i 31" gets invoked from the autostart folder.
This works often, but unfortunately sometimes krb5-ticket-watcher fails to start up and aborts instead with a pop-up error
I couldn't detect any system tray on this system.
I suspect that krb5ticketwatcher looks too early in the initialization sequence for the system tray, and rather than waiting for a few seconds and then trying again, it gives up instantly.