In recent discussions on a foreign forum I participate there were some references for running XBMC in Kiosk Mode; I've written a tutorial (very minimalist) to run XBMC in Kiosk mode using openSUSE 12.3 in an old laptop (as discussed in the original thread in the foreign forum).
The tutorial is here: https://pt.opensuse.org/SDB:Tutorial_XBMC
Any translators willing to translate it to other languages, feel free to do it; it's currently written in European Portuguese (the language spoken in Portugal and all former colonies except Brazil).