Google has an odd definition of "soon." For example, five of the countries that just received access to Google Play gift cards were first told that they were coming "soon" almost five months ago, and the last one has been waiting a further six weeks. Oh well, I suppose it's best not to look a gift card in the mouth. Belgium, Denmark, Finland, Ireland, Norway, and Sweden have been added to Google's gift card system, and merchants should have gift cards in stock well before Christmas.
Belgium, Finland, and Ireland all get cards with Euro values of 15, 25, and 50, while Denmark, Norway, and Sweden get 150, 250, and 500 Krone/Krona cards. Google has also posted its support page for Belgian Play Store gift cards en Français, given the country's high population of French speakers. Presumably the cards will work the same no matter where you buy them or in what language, so long as you redeem them on the Belgian Play Store interface.
This brings the total number of countries where Google Play Store gift cards can be purchased up to 28. At the moment no extra countries or locations are "coming soon." Hopefully by the next time the holidays roll around, a few more places will be open.
Source: Google Play Store support