Terrible comparison. A dick move maybe but not a scandal.
Google App Engine:
* Not the dominant hosting platform. Not even close to being the dominant.
* Maybe a million dollar product. Certainly not a billion dollar product.
* In beta/preview until just now with developers knowing pricing had not been set or could be changed.
* Optimizing your application properly can negate most if not all of the pricing increase.
* Open source alternative framework available if you want to keep using the same APIs.
Apple App Store:
* Dominant market position with only the Android Market coming close.
* Billion dollar product.
* Existed as fully launched for several years.
* Set percentage. You can't change it other then making your app free.
* No open source alternative that supports the same APIs.
Beta/preview products can and will change.