Finally, the free iOS 4 upgrade should give Apple some high ground on Android among developers. This is the first time iPod touch users have not had to pay for a major OS upgrade, thanks in part to looser accounting rules. But too much is at stake, and Android’s fragmented installed base will become a louder talking point. Apple wants every customer on 4.0 as soon as possible, and wants every developer to know that it’s safe to move forward without looking back. Don’t be surprised if Apple becomes unusually vocal about the number of users running 4.0.