Re. /etc/event.replace.d/

Many system services place the upstart file in /etc/event.replace.d/, but then postinstall copies it to /etc/event.d.

I guess this is a way of ensuring that the script is only really put where upstart will find it once the whole package has been extracted.

So I officially state:
BEGIN:
You can wipe out the folder if you like.
It will never be used during booting.
The only thing that could happen is that you install some program (which comes with an upstart script), and the script is placed there.
If so, GOTO BEGIN (if you like).

Next is /etc/rc?.d. Thanks @Hurrian for confirming that the N900 boots just fine after deleting those folders. Just in case I want to figure out WHO/WHAT created those folders in the first place.