I was also a Zaurus user, and the functionality can be had here, too.

In a nutshell, I think the trick is to enable "Soft poweroff", by uncommenting the last sections of /etc/systemui/systemui.xml. To get functionality exactly like the Zaurus, edit /etc/mce/mce.ini and set the PowerKeyLongAction to softpoweroff. That way, holding down the "Power" key should do the same thing as holding the "Cancel" key did on the Zaurus.

Correct me if I'm wrong, I haven't done much editing of mce.ini, but one of the first things I do when I reflash the N800 is to edit systemui.xml to enable Soft Poweroff, and move that item to the top, so that I can put it to sleep by pressing Power, Enter.