While there's a ton of Android apps, I'm pretty sure there's already a large part that targets iOS first simply because of how long iOS/app store has been around compared to Android.
Speaking as someone who has developed on both platforms, it's definitely my experience. And that includes starting with an Android app and porting it to iOS - half of the stuff I had to add to Android to make it usable I discovered they had already built into iOS. Not to mention the poor choice of defaults, coping with device fragmentation, and the difficulty making Android apps look attractive via-a-vis iOS.
I haven't built ICS apps, though, so perhaps it's getting better.
