A tale of Windows store success: the developer making $30k a month - Neowin

"But, if you were a developer and did believe in Microsoft's vision for the OS, you could have cashed in. One developer, Kevin Ashley, has written up his story about how he is making $30,000 a month in the Windows Store. This success does not come lightly as many developers would kill for this kind of revenue and seeing that it can happen in the Windows Store shows that Microsoft's Windows 8 platform is growing rapidly and should be taken seriously. One of the applications that Kevin built that is currently in the store is called Card Games Chest, which is free but uses in app purchases and advertisement to generate revenue.

One interesting tidbit from his post is that when he looked at the current markets, Windows Store provided the best opportunity:

When I presented to the largest iOS meetup in Silicon Valley, I asked the audience of 200 pro-iOS developers a simple question: do you believe as a new developer I can enter Apple Store market today with a bunch of Solitaire games and make this kind of money? Their response was: you’ll waste your time, this market is too saturated!"