Distimo noted that Microsoft’s Windows Phone 7 Marketplace and Google’s Android Market were “clearly ahead of the other app stores in terms of growth rates” during January 2011, with growth of 30 percent and 18 percent respectively.

Due to the relative size of the two stores, the number of apps added to Android Market was significantly ahead of WP7 Marketplace – at 22,997 and 1,603 respectively. According to Distimo, Android Market is the only store to have more free than paid-for apps, and the proportion of free titles increased again during January 2011.

Interestingly, the store which saw the smallest growth was Apple’s App Store for iPhone, which grew by just 1 percent – although this store is already twice the size of its rivals. It may be a case that developers are now starting to feel that the App Store has passed its optimum size, and that there are greater opportunities from other platforms – where achieving visibility is not as tough.

The overlap of applications between countries is over 97 percent for both Android Market and Windows Phone 7 Marketplace, although for the top 100 apps, the overlap is much lower in Microsoft’s store than Google’s. This is said to indicate that that it is “much easier for consumers to find locally popular content” in the former than the latter.

It was noted that Microsoft has “already attracted some of the largest cross-store publishers,” but that it “still has a long way to go” to match the totals of Android Market or the Apple App Store. Of the “top 200” publishers which make products available for at least two stores, more than 150 are present in the App Store for iPhone, almost 150 are in Android Market, and 57 are in WP7 Marketplace, although WP7 is outscored in this metric by the App Store for iPad, BlackBerry App World, Ovi Store and even Palm’s App Catalog. With WP7 Marketplace being a relatively new entrant to the market, Distimo said that this is “clearly a platform that large developers are watching closely.”