Just approximately 600,000 more apps needed to catch up with Android and Apple.
It was just last month when the platform hit the milestone for 40,000 apps. It seems plausible that the new adoption of Windows Phone to Nokia devices has spurred developers on to adapt to the OS.
All About Windows Phone claims the Microsoft milestone has been hit as a result of around 265 new items being added to the Marketplace each day.
However, while this may be a peak number of apps for the OS, it pales in comparison to Apple's App Store, which has around 600,000 apps and Google's Android Market, with around 500,000 apps.
On the other hand, WinPho reached the milestone in 14 months, while it took Android 19 months to get to 50,000. They were both outdone by iOS though, which achieved the milestone in 12 months.

http://www.mobile-ent.biz/news/read/...00-apps/016570