> It has to be related to Unity global menus.
> I'm using Inkscape on Debian Testing (Gnome Shell) and keyboard
> shortcuts are displayed correctly.

OK Good to know it only affects Unity based systems.
That said, all other applications i tested on Ubuntu 12.10 - GIMP, GEdit, Firefox, Chromium, LibreOffice work fine with the Unity menu.

I will look into it https://bugs.launchpad.net/inkscape/+bug/998276