Yup. Remember: alarms have to sound

If my list is right, the following things run when ACTDEAD:

welcome (just echo)
rcS
dsme
dme
kernel-power
sshd
actdead (just echo)
cmt-act-dead (kill modem)
console (serial console if R&D)
dbus-actdead (same as "dbus", swap USER/ACT_DEAD start/stop)
alsaped (ALSA policy daemon)
dsme-dbus
hal
rcS-late
ohmd
sgx
xomap
mce
n900-fmrx-enabler (yup, enable FM receiver
ohmd (yes, it's activated twice..)
pulseaudio
clock-daemon
hildon-control-panel-personalisation (make sure we have a theme!)
rc-clean-fail-thumbnail (absurd in ACTDEAD mode)
xsession

and then, when X is up and running:
00settings
01dbus (dbus session, system already started)
03alarmd (get them alarms ringing!
10sapwood
14osso-systemui
15matchbox (start WM, why? because we can [*]
99initdone
[*] OK, I suppose matchbox is started (and the theme framework setup) so that you get the familiar alarm UI if necessary.

When I have some more time I will make a post for each system service (or for a group of them) with an explanation of what it does. I guess a Wiki would be the best way, but I just can't find a way of creating an article

Add.: and more importantly, the reboot and shutdown process has to be duly documented.