Market researchers at Localytics looked at the Apple iPhone 3GS and Motorola Droid and upgrade rates to the latest respective OS versions -- iOS 4.0 and Android 2.2 "Froyo"  -- over their first two weeks of availability.  What they found was that nearly twice as many Android users upgraded to the latest OS as iPhone users.

The study showed the dramatic benefits of Android's over-the-air OS updates -- something Apple has either been unable or unwilling to implement.  IOS 4.0 saw a steady crawl upwards in adoption rates, that allowed it to temporarily get ahead of Android 2.2.  

But when the Android OTA packages landed, in a single day the Android 2.2 adoption jumped incredibly from around 42 percent to around 92 percent.  By the end of two weeks, Android's upgrade totals had reached 96 percent, while Apple had a mere 56 percent.

One thing Loyalytics says the study shows is that iPhone users are using iTunes less.  If they had plugged into iTunes they would have been prompted to update, but many users still appeared not to have connected after almost two weeks.  This may be a result of Apple enabling over-the-air content downloads from its iTunes store, which is directly accessible from the iPhone.

However, the study brings mixed news to developers on both fronts.  For Android developers the rapid updates are good in a way, because they can be assured a homogeneous platform.  It can also be bad, because if an update breaks your app, you may only have have a couple of days to fix the problem before the majority of users can't use it.

For iPhone developers the opposite is true.  The platform is more heterogeneous in terms of OS versions, which can be confusing as to which versions to target and when.  On the other hand, iPhone devs have more time to fix bugs created by OS updates.

The researchers conclude:

The extent to which the iPad is or isn’t cannibalizing PC sales is being debated. But it seems reasonable to assume that even fewer iPads will be plugged into computers than iPhones, suggesting that iPad upgrades to iOS 4.2 later this year will lag iPhone upgrades. At some point, Apple will probably need/want to provide OTA upgrades to both the iPad and iPhone, at least over WiFi.

Of course as anyone who knows Apple could tell you, the company is sure to take adopting this new feature at its own pace, however fast or slow that may be.