The following packages are involved in WiFi on the N900:
connui-conndlgs-wlan (provides dialogs for WiFi connectivity stuff)
connui-iapsettings-wlan (the wizzard for setting up a WiFi network)
icd2-network-wlan-config (provides some stuff connected to WiFi configs, no binaries in this package)
libicd-network-eap (eap module for icd2)
libicd-network-ipv4 (IP module for icd2)
libicd-network-wlan (WiFi module for icd2)
libicd-network-wps (wps module for icd2)
osso-wlan (WiFi daemon, open source)
osso-wlan-security (WiFi security daemon)
osso-wlan-dev (dbus interface for various WiFi things, open source)

Coming up soon is some info on the dbus calls and other external things used by some of these binaries.

Links to relavent header files are here: (unless otherwise specified the relavent dbus interfaces are documented in these 3 header files)
http://www.cncmods.net/files/dbus/wlancond-dbus.h
http://www.cncmods.net/files/dbus/eap-dbus.h
http://www.cncmods.net/files/dbus/osso-ic-ui-dbus.h

First up its libiap_dialog_gtc_challenge.so
It is activated via the dbus method com.nokia.icd_ui.show_gtc_dlg and returns its result via the dbus signal com.nokia.icd_ui.gtc_response.

Next up, its libiap_dialog_mschap_change.so
It is activated via the dbus method com.nokia.icd_ui.show_mschap_change_dlg and returns its result via the dbus signal com.nokia.icd_ui.mschap_change

Then we have libiap_dialog_private_key_pw.so
It is activated via the dbus method com.nokia.icd_ui.show_private_key_passwd_dlg and returns its result via the dbus signal com.nokia.icd_ui.private_key_passwd.

Then comes libiap_dialog_server_cert.so
It is activated via the dbus method com.nokia.icd_ui.show_server_cert_dlg and returns its result via the dbus signal com.nokia.icd_ui.server_cert.

Next up comes libiap_dialog_wps.so
It is activated via the dbus method com.nokia.wps_ui.show_select_method (undocumented unfortunately although it appears to take a string and an array of strings as arguments) and returns its result via the dbus signal com.nokia.wps_ui.method_sig (also undocumented unfortunately although it appears to take a string and a bool as parameters)
It also calls the dbus methods com.nokia.icd2.select_req and com.nokia.icd2.disconnect_req and listens for the signal com.nokia.eap.signal.wps_success.

More to come later.

I made a full replacement of libicd-network-{wlan,eap} almost 6 years ago, called libicd-network-wpa :

http://svn.javispedro.com/view/libic...ork-wpa/trunk/

http://libicd-wpa.garage.maemo.org/

To be honest I recommend avoiding ICD like the plague since most of it seems to come from symbian...