According to WZOR, Windows 9 will be similar to the desktop operating system we know today and that Microsoft plans to bring back the Aero interface, but in a different fashion than before. He also claims that Windows 9 will arrive in 2014, which is in line with previous reports that Microsoft is moving towards a yearly release cycle for Windows. Bear in mind that Windows 9 is likely a codename, the actual name of the operating system may be different.
There's also some talk about "Windows 10", WZOR claims this will be a full "cloud OS" and that Microsoft hopes to get an internal concept working by September 1st, but it will likely take a lot longer until Microsoft shows this to the general public.
Another rumor is that Microsoft plans to merge Windows Phone and Windows RT, but a timeframe for when this is supposed to happen isn't provided.
WZOR also claims that more details about the aforementioned rumors will become available in September.