As it currently stands, should you wish to develop for both Windows 8 and Windows Phone, you'll need to take out two subscriptions - one for each platform. WPDang now reports that Microsoft is looking to combine both into a combined account, making it easier for developers to move from one platform to the next and cover not only the desktop but also the smartphone too.
It's worth taking this with a grain of salt, but the website notes that Redmond will officially unveil the new accounts, merging both communities together. How much would the new accounts set developers back? WPDang reports that a fee of $19 will be in place, with team accounts listed for $99. It's understood that this would not mean both app stores would be combined.
While this is strictly rumour, WPDang has been a rather solid source in the past and this is a move we could certainly see Microsoft making. The company has been attempting to unify its Windows platforms since Windows Phone and Windows 8 were originally released. To enable developer to take full advantage of both platforms with a single account and subscription makes sense.
Source: WPDang; thanks, answer1626, for the tip!