also found this on the forums from a GOG team member:
I know that some people will have questions about this so here are some exceptions for the promo:
Square Enix, Bohemia Interactive, Capcom and Interplay catalogues will all only be on promo for one week.
Games which were released recently are not included in the promo. A handful of other games are also not included for various reasons.
Eador titles are 30% off and Night of the Rabbit is 20% off.