In this question https://answers.launchpad.net/ubuntu/+source/linux-source-2.6.22/+question/13022 some people said that the iwl3945.ko was in Gutsy.
I think it should be in this package because there is the ucode for that driver.
root@matteo-laptop:~# modprobe -l | grep iwl
/lib/modules/2.6.22-12-generic/ubuntu/wireless/iwlwifi/mac80211/origin/net/mac80211/rc80211_simple.ko
/lib/modules/2.6.22-12-generic/ubuntu/wireless/iwlwifi/mac80211/origin/net/mac80211/iwlwifi_mac80211.ko
/lib/modules/2.6.22-12-generic/ubuntu/wireless/iwlwifi/iwlwifi/origin/iwl4965.ko
matteo@matteo-laptop:~$ locate iwlwifi
/lib/modules/2.6.22-12-generic/ubuntu/wireless/iwlwifi
/lib/modules/2.6.22-12-generic/ubuntu/wireless/iwlwifi/iwlwifi
/lib/modules/2.6.22-12-generic/ubuntu/wireless/iwlwifi/iwlwifi/origin
/lib/modules/2.6.22-12-generic/ubuntu/wireless/iwlwifi/iwlwifi/origin/iwl4965.ko
/lib/modules/2.6.22-12-generic/ubuntu/wireless/iwlwifi/mac80211
/lib/modules/2.6.22-12-generic/ubuntu/wireless/iwlwifi/mac80211/origin
/lib/modules/2.6.22-12-generic/ubuntu/wireless/iwlwifi/mac80211/origin/net
/lib/modules/2.6.22-12-generic/ubuntu/wireless/iwlwifi/mac80211/origin/net/mac80211
/lib/modules/2.6.22-12-generic/ubuntu/wireless/iwlwifi/mac80211/origin/net/mac80211/iwlwifi_mac80211.ko
/lib/modules/2.6.22-12-generic/ubuntu/wireless/iwlwifi/mac80211/origin/net/mac80211/rc80211_simple.ko
/lib/firmware/2.6.22-12-generic/iwlwifi-4965-1.ucode
/lib/firmware/2.6.22-12-generic/iwlwifi-3945-1.ucode
/lib/firmware/2.6.22-12-generic/iwlwifi-3945.ucode
/lib/firmware/2.6.22-12-generic/iwlwifi-4965.ucode
Gutsy lum commit 3feaf7e32866232 4dec24e16d82b3d 291f82a48b enables the build of iwlwifi, but modifies the source such that this module is not automatically loaded, e.g., removes MODULE_DEVICE_TABLE from iwl-3945.c