Thanks for the help. That's just the kind of info I was looking for.
I wrongfully assumed giving the kernel version would tell my distribution. It's Squeeze (Stable).
apropos regulatory Gives no output for me. I guess(?) crda is 'built' into the kernel in this distro, like mentioned on that page.
I have found /usr/share/dbus-1/system-services/fi.epitest.hostap.WPASupplicant.service thanks to that previous post.
Although it also mentions:
chmod 0600 /etc/wpa_supplicant/wpa_supplicant.conf
Where they finally specify the exact location of that file (that doesn't exist on my system yet). I can't find anything named nl80211 on my system, so I assume(?) it is using some older method.
I'm leaving the other thread open for the specific wlan question I had.