It's not often we see an API "go on sale". But that's what Google is doing with their announced a Google AdWords API. They have a new version update but along with it, they have "holiday season API sale pricing". The details of the holiday sale are spelled out in the October 20 AdWords API blog post "Happy Holidays! Enjoy more API units":
Square has launched the Register API for Android only a couple of months after releasing the API for iOS. The API allows developers to build end to end point-of-sale solutions that utilize Square's entire payment platform, or that integrate with third party infrastructure and applications.