I tried Prey www.preyproject.com. Looks promising. Localization and basic system report seems to work (they showed my position quite accurate in google maps); though, someone would need to put in some work in order to get webcam images and more device specific modules to work.

I suggest to use alarmd since we don't have crontab.

It is written in plain bash and very modular.

Do not try the "Lock Device" option, it seems that this one is now rebooting my N900 right after the Desktop appears.