It has been speculated for some time that Microsoft would deliver Windows 8 to all of the devices in its portfolio. At the annual shareholder meeting, Steve Ballmer said "We are driving Windows down to the phone with Windows 8" according to Business Insider.
The unification of all of Microsoft's many platforms has been speculated for years. But, this new information from Ballmer would, on the surface, indicate that Windows 8 will be deployed across nearly all of its platforms to create one, massive, ecosystem.
BI speculates that this does not mean that the next version of Windows Phone will look exactly like Windows 8 that we know today, it most likely means that the two platforms will share the same NT kernel.
This move should make it easier to port applications from the desktop to the phone environment as Microsoft will only have to maintain one kernel for its various platforms. Of course, this could all be retracted by Microsoft much like they did with Ballmer's last big reveal that the next version of Windows will be called Windows 8.
[Update] It appears that it was a closely worded section of Ballmer's speech that gave the misinformation. The transcript, from BI, is posted below:
We've got broad Windows initiatives, driving Windows down to the phone with Windows 8, you'll see incredible new form factors powered by Windows, from tablets, small, large, pens, smaller, bigger, room-sized displays.
The pause in the speech or no pause in his speech is what caused the confusion. While hopes may be dashed, we doubt this will be the last we hear about this topic.