Clearly the Android Market is growing rapidly, and there’s no reason to even mention the Apple App Store, which just breezed by the 100,000 iPad app marker. But we can’t leave the little guys out, especially when their growth is also relatively impressive. Specifically,Microsoft’s Windows Phone Marketplace is reported to have passed 25,000 applications by a site that tracks the app store’s activity.

That number is a bit questionable as other app trackers have listed the Windows Phone Marketplace as just under the 25,000 mark. Either way, Microsoft’s app store is growing, and at a faster rate than it had been. From the beginning of its launch in November to the end of March, the Windows Phone Marketplace only boasted 11,500 apps. That’s about 2,300 apps per month. Three months later, another 13,500 apps have made their way to the Marketplace, an average of 4,500 apps per month. With Mango headed our way, there’s no reason to think this rapid growth won’t keep up its pace for a while.