I like to check in on Apple's top grossing applications - it's a good indication of mobile app and publisher trends. And from time to time, I have written about those trends. ... and here is a relatively important trend: each of the current top iPhone apps is freemium (">we've seen hints of this in the past, but never to this degree). Eight of the ten top grossing apps are free and fifteen of the top twenty-five. These come from a variety of publishers and are almost entirely games - only one app is not a game (#21 iMuscle is a health related app - $1.99).

This is a natural evolution of improved game mechanics and better in-app purchasing flows.... both lead to more effective premium upgrades / monetization while preserving iTune's distribution potential. For example: In January 2010, only three of the twenty-five top grossing apps had in-app purchasing enabled. Now, most of the top-grossing apps are distributed as free downloads and monetize in-application.