The ease of development in the iPhone SDK, combined with the huge success of the device and Apple's own promotion revolving around how many apps are in the store, mean that the platform is taking off like a rocket. Sure, numbers aren't necessarily the best indicator of quality (anyone want to speculate how many of the 20,000 apps have to do with farting or belching?), but the fact is that people are both developing and consuming apps from the App Store in gigantic numbers. How long before we reach 50,000 different applications on the iPhone? A million?