Microsoft also made adjustments for things like foreign exchange rates, taxes and "market-specific pricing customs," and suggests that developers visit Dev Center to make any necessary changes. As far back as last September, we told you about Microsoft's plan to merge both app stores at around the same time that Windows Phone 8.1 is released. Combined, the two stores now offer 400,000 apps.
Eventually, developers will work on universal apps that will work on desktops and handsets alike.
source: Windows via WMPoweruser