Bad news, guys.
When using Maemo py2deb, putting
p.postinst = "control/postinst"
in my script puts a literal string "control/postinst" as my postinst script, not the contents of that file.

jolouis, what version of py2deb are you using? I'm using the one from Diablo Extras.

The good news is that the control scripts are the only broken thing with the package... Oh, and the .png file for my icon doesn't seem to show up in App Manager...