Today, the Windows Phone Marketplace, just four and a half months after launch, hit 10,000 apps making it the fastest growing smartphone app market yet--beating out the iPhone and Android in terms of rate-of-growth. Currently, the Windows Phone Marketplace adds about 100 apps a day with an average price of $2.10 and that growth rate seems to be slightly increasing as of late. By comparison, the iPhone was adding 70 apps a day when it hit 10K--a feat that took Apple 142 days with an average app price of $3.50.

At the current rate of growth, Windows Phone should expect to overtake #3 RIM's market within the next six months. Currently, Blackberry users have about 20,000 apps available--but they launched in April, 2009 and were only adding about 900 apps a month. By comparison, Windows Phone is adding nearly 3,000 apps per month, crushing RIM.

While we can of course debate whether all 10,000 apps are worthy of mention, we think it's a great sign that nearly six months out, Windows Phone developers are pumping out as much if not more apps today than they were at the beginning--meaning this wasn't a temporary surge, but a consistent commitment and interest.

Flashback: Marketplace hits 1,000 apps (Oct 23, 2010); Marketplace hits 5,000 apps (Dec. 28th, 2010)

[Of course, with all big news there is a down side: we mentioned how after 10K we will be retiring the 1K marks every few weeks and instead will hit the next 5K. So we'll see the "awww yeah guy" in a few months from now.]

Source: Windows Phone Applist, Seeking Alpha (for RIM info), WP7Applist, In Numero