Windows 9 is supposed to be unveiled at the end of September. The new Windows Phone 9 OS is rumored to arrive for developers in December.
Microsoft is on a never before seen fast release cycle for operating systems. Windows 9 is supposed to be unveiled on September 30th. According to ZDNet, Windows 9 will be released as a technology preview at the end of September or early October. Full release is supposed to be in spring of 2015.
The next Windows Phone OS is likely also coming in Spring of 2015. A new report on TK Tech News says that developers will get Windows Phone 9 in December. The report claims that Windows RT and Windows Phone OS are going to be merged with a new "retro name." MS DOS? Just kidding.
TK Tech News claims that they have more Windows Phone 9 leaks coming soon.