Market of Android and iOS applications is almost tight, as for Windows x86.
New market will be soon, common for tablets, mobile phones, TV sets, gaming consoles and desktops (touchscreened !): Apple and Google have no such markets yet.
Seems, Microsoft might\will get a piece or their pie.
Time to think about Basic4WinRT, Erel
You will always need a Windows 8 PC to develop Windows Store apps as the WinRT libraries are not available for Windows 7 although the free Visual Studio 2012 Express for Windows Desktop will run on Windows 7 SP1 but of course will only target x86/x64 and not WinRT.
I've been a little burned by M$ and their Windows shifts too much...especially in handhelds, but I don't limit my dislike to that only as Win Vista/7 aren't the greatest either. I liked WinMobile and Commercial/Industrial handhelds still develop devices for it, but nothing really moved to Win Phone. I don't think it will take off much, just as Win Phone didn't, until they make something for commercial devices. iPhone/iPad/iTakeYourMoney isn't rugged enough and only Android seems to be moving into that sector right now which is why I got B4A to begin with.
I don't like the shift to Market Place so much either. iPhone likes to restrict everything to their products and their market. Android allows other markets and other app side loading without even coming from a market. If Windows 8 goes more open like Android and comes to commercial I'd think about supporting them. If they they limit apps to being from their store or pull another Zune-Only connection option like they did with Win Phone they can keep their garbage.