I'm preparing the next release (0.7.1-1), but I have some packaging & extras related questions:

1 ) What to do with data files? I took a look at pingus package sources to understand what they're doing with them. While already better than no distributing data files at all it seems like a fragile solution -- e.g. it removes all data files in preinst script. In OpenTTD I would need to delete only files installed by the package (so that I don't delete the commercial user installed files). If I don't delete files at all in preinst dpkg-deb fails with some error message about doing links "for backup reasons" (links? on vfat?) .

I also though about doing more than one data package:
openttd-data-on-internal-card (default)
openttd-data-on-external-card
openttd-data-on-rootfs
openttd-data-stub (does nothing but satisfy openttd' dependencies).
This fixes the fact that installing pingus or most data packages require user interactivity ("do you want to install to card? yes/no") by just installing all data files to card by default but allowing the power user to install on external card or rootfs doing apt-get install "openttd-data-on-external-card".

Also whenever Fremantle comes it will break all of this.

2 ) There's already a (few months older) openttd package in extras-devel. What's the usual approach to this?

3 ) And of course... did this work for you?

BTW. In 0.7.1-1 I've moved saved games to My Documents/Games/OpenTTD (where they should be), added support for the fullscreen button on the main menu window, and hided the mouse pointer by default.
Also, the OpenTTD team fixed a lot of bugs.