Due to licensing constraints, we can't ship any locale with a dictionary other than en-US. The first run pages (and updated pages) for these locales should offer direct links to install the relevant dictionaries.
I guess you was talking about Firefox only. Thunderbird currently have a link on its local startup page towards http://downloads.mozdev.org/dictionaries/spell-ab-CD.xpi. I guess this should be changed too ?
The format that the localized pages need to link to for adding the dictionary is: https://%LOCALE%.add-ons.mozilla.com/%LOCALE%/firefox/%VERSION%/dictionaries/ Presently that goes to the "Dictionaries" category on AMO, but shaver has told me that in the bright future of Remora, it will go to a page that is not only the category for all dictionaries, but also uses the %LOCALE% information to provide that locale's dictionary as a "featured extension" (ie: front and center)
Well we're not at Remora yet unfortunately, but Shaver whipped up a bit of last minute dynamic magic and this system is now in place.