このところ、Android アプリのマーケットが急激に成長しています。

Android Market will become biggest mobile platform by August 2011 | research2guidance

Given the same growth rates (number of apps) as in the previous months the Android Market will reach 425,000 apps in August surpassing the Apple App Store.

出典：Android Market will become the biggest mobile content platform in the world by August 2011 - research2guidance

アプリの数で、8月にはiPhoneアプリと同等、その後も勢いが衰えること無く、増えていくと予想しています。

The "free" culture of the Android Market has been one of the main characteristics of the Android ecosystem since its launch. Over the last few months there has been a tendency for publishers to try to shift the balance by submitting more paid apps. In April, the share of free apps submitted to the store slightly decreased to 60%.

しかし、Androidアプリは「フリー(無料)文化」があり、ビジネスになりにくい部分がありました。また、Android Marketにおける無料アプリのシェアは64%でしたが、4月にサブミットされた無料アプリのシェアは60%ということで、徐々に有料アプリが増えていくと思われます。