The Android Market took 31 months to reach 200,000 apps, while the App Store only took 22 months. After that, though, the Android Market kicked into high gear, and needed only four additional months to add another 100K apps and surpass the 300,000 mark, while the App Store needed eight more months. Additionally, the time between 300K and 400K was only 4 months for Android and 7 months for iOS.
Google's Android Market is close to another milestone of the 100K kind: it has almost reached 100,000 active publishers.
Of course, the vast majority of these developers in the Android Market are making their apps free. In fact, the percentage has continued to increase; in April of 2011 60 percent of the Android Market apps were free, compared to 68 percent by the end of 2011.
Many of these are freemium apps, which rely on in-app purchases to garner revenue. That said, iOS still brings in far more money than Android. Apps for the iPhone alone, not counting the iPad, brought in about four times the revenue of the Android Market, according to Distimo's year-end report.
The iPad's revenue was also greater than the entirety of the Android Market's.