I won’t call you either of those. We had tutorials on both iOS and Android IAP, but replaced them with the guide. The information in the guide along with the sample app and the examples in the docs should paint a complete picture of how to get started.
We would love to actually write a blog post on this, but the topic is too broad and deep to put into a tutorial form. We are approaching 5 different IAP vendors (6 if you count the fact that using Fortumo for Nook, is different enough than using Fortumo for Android that you would have to cover the differences).
In addition, there are too many different ways that developers want to use IAP that any attempt at tutorial would just scratch the surface and would be very redundant with the Guide + Sample App that we already have.
Now if there is a specific IAP topic where we could have a succinct, limited scope then sure, we will do that. But what would you want that topic to be?