If you are interested in App Stores and comparisons between them, then you might like to take a look at Distimo’s presentation from Mobile World Congress 2010. There are some great slides. For example, here’s one comparing free vs paid for the various app stores…
It’s noticeable that Android has by far the highest percentage of freeware. I guess this is because most commercial entities have been taking a ‘let’s wait and see’
attitude towards Android. A higher proportion of applications are by individual developers, such as myself, who have created freeware for fun and to learn more about the platform. I think there may be a higher percentage of paid software in, for example, a years’ time when the many announced devices have become available.