If you really want to know what's going on in the wonderful world of Android, check this out:
Visualized: Google's Android Fragmentation vs. Apple iOS - DailyFinance
Visualized: Google's Android Fragmentation vs. Apple iOS - DailyFinance
My own concern: under these conditions, it must be frustrating/discouraging/offputting for developers to write apps that will run reliably under all variations of Android. How did this situation come about? MS, after all, has always put out an OS that runs successfully on a huge variety of PC's, probably by insisting that every mfr. adhere strictly to its guidelines. Google, by contrast, must be very weak-kneed in caving to the special requests of individual mfrs. If I am right, this is a huge corporate mistake.