You have to put a credit card on file to use the promocodes. So, they've just made it much easier for users to impulsively buy other apps in the future, and they've shown people how to use the app store. Not a bad marketing plan!

Personally I planned on making zero webOS app purchases in anticipation of installing Android. But now that my CC is on file, I'll probably have Angry Birds on here by the end of the month. :p