Quoting John Fletcher net@twoedged.org:
Does anyone know whether it's possible to use t() with a non-English base language?
Yes.
Does anyone know the status on this? Can I use Spanish as input to the t() function?
See http://api.drupal.org/api/function/t
t('siempre te esperamos'); and a translator translates to 'you are welcome' for the English version.
-- Earnie http://r-feed.com Make a Drupal difference and review core patches.