Microsoft’s app store for Windows Phone 7 has been growing at an increasingly alarming rate. The app store that launched with only a handful of apps has been steadily putting up more apps available for download over the past two months. It hit 1,000 apps on October 25, 2,000 on November 8, 3,000 on December 1, and as of today, it now has 4,000 apps! This definitely shows the developer interest in the operating system. If they keep growing at this rate, the Windows Marketplace will soon surpass Android and even hit the magical 300,000 apps of the iTunes App Store in no time- assuming the other markets don’t grow as fast. The increase in the amount of WP7 apps should definitely generate more user interest in the operating system. Looks like Microsoft accountants are going to be real busy dishing out checks to app developers, especially since they announced that payments will be given out every month starting from next year onwards.