I wanted to have my 770 do dynamic dns update. In the past, due to ignorance of anything better I've just written a shell script that gets cronned every 15 mins or so that sees if anything's changed, and if so updates my IP with curl. But the 770 doesn't have cron.
So I went looking for some sort if interface up hook.
/etc/init.d/ was the only place I knew to look - but it turns out that scripts in there just get called when the interfaces go up, not when a wlan connection happens, so that was no dice. I couldn't find anything else, and ended up finding someone had ported a working cron to 770, so for a while I just used that.
Then today, I found out about dbus, which led me to
/etc/udhcp, and bingo, that was it. I added a line that calls my dynip script at the appropriate spot in
/etc/udhcp/udhcp.script, which seems to be the one that actually runs, and it works great - only checks/updates on wlan connect.