Microsoft’s Windows Phone marketplace now has passed 25,000 apps, reaching the milestone in 263 days from when the application store launched.

Marketplace statistics have been tracked by Windows Phone Applist, which counts 25,018 applications at the time of writing, adding 1947 apps in the last two weeks alone.

Winrumors surveyed rival app tracking website WP7applist which currently tracks 24,784 applications worldwide, with 4,025 inactive apps. According to the site, 51% of apps are available for free and the average price is $1.48 per paid application.

In December, we reported that despite a slight slowdown through the Christmas season, the number of apps on file for Windows Phone 7 had grown at a very steady clip, breaking the 5,000 mark, adding 4000 apps in just over 30 days. Two months later, the marketplace passed 8000 applications, with 28,000 registered developers and over 1 million developer tools downloaded.

Microsoft announced it had passed the 15,000 app mark in April, adding 3,000 apps in under a month.

Microsoft’s platform will inevitably be compared to Apple’s App Store, which recently passed 100,000 iPad applications. If you wondered how long it took Apple to reach 25,000 apps – it took 238 days. Comparing the two, Microsoft has managed to engage developers despite the growth of both iOS and Android operating systems.

A number of new vendors are working on Windows Phone handsets that will be powered by Microsoft’s new Mango firmware. The Redmond-based giant will hope it can tempt more developers to the platform, taking advantage of the new features it has incorporated.