Amazon has made a big dent in Apple's hold on the table market with its Android-based Kindle devices. Android, of course, is the operating system created by Google. Now, according to The Verge, Amazon is taking a bit of a shot across the bow at Google, and introducing an API to allow users "Amazon-based ads in their apps in lieu of (or in addition to) ads from other networks - Google, for example."
It's a complicated relationship. Google provides the OS for free, but makes money, in part, through ads placed in the apps in its marketplace. Amazon's Kindle devices make up a small but significant part of the Android eco-system, and if the API is successful enough Google may have to take a look at how it allows hardware companies to use its software.