Microsoft offered Windows Phone 7 users download 12 apps a month from Windows Phone Marketplace store

Some 36,000 individuals and studios are members of Windows Phone developer community, with 1,200 more joining every week

Windows Phone 7 Windows Phone 7: there are 11,500 applications available on the Windows Phone Marketplace store.

Microsoft may be keeping its cards close to its chest on sales of Windows Phone 7 handsets, but the company has released some stats on its smartphone operating system, with the aim of persuading app developers to throw their weight behind it.

In a long post on the Windows Phone Developer Blog, Microsoft's Brandon Watson outlines some of the numbers that he says illustrate WP7's momentum. For example, 36,000 individuals and/or studios are now members of the Windows Phone developer community, with 1,200 more joining every week.

Some 40% of these registered developers have already published their first app or game for WP7, meaning 60% have not yet done so. Watson also says that the average time to certification – meaning the time it takes to get an initial pass or fail – is 1.8 days, with 62% of apps passing on their first attempt.

There are now 11,500 applications available on the Windows Phone Marketplace store, with 7,500 of those being paid apps, while 1,100 are using Microsoft's mobile advertising tools to generate revenues from in-app ads.

Watson makes an interesting claim too: "Based on the conversations we are having with some of our developers, many are telling us that they are seeing more revenue on our platform than competing platforms, despite the fact that we cannot yet match the sheer number of handsets being sold."

It is hard to evaluate that claim without knowing which developers are saying this, of course. Microsoft has consistently pitched WP7 as a potentially lucrative platform for developers, where there is less competition (for now) than iPhone, and a greater willingness to pay for apps than Android. The message certainly isn't falling on deaf ears, but more specific examples are required to judge how well Microsoft is delivering on that promise.

Watson adds that Windows Phone 7 users are downloading an average of 12 apps every month, although there is no further information on how many of those are paid versus free, or any stats on the actual revenues being generated on the Marketplace by developers. More information is likely to come at Microsoft's MIX11 conference, which starts on 12 April and is likely to put an emphasis on making developers feel comfortable on WP7.

"We look forward to further increasing the engagement and transparency with our developer community, including more visibility into the update release schedules, roadmaps, access to early builds of the new OS and more time with our team," he writes.

If Microsoft is to prove analysts like IDC and Ovum right – who as we reported yesterday both see Windows Phone growing to the point where it will be hot on the heels of iOS (or even ahead of it) in three or four years' time, developer relations will be a critical element to get right.

Games developers had their say earlier this week, but if you've released an app through Windows Phone 7, now would be the time to pitch in.