A new version of Windows Phone, Windows Phone 8, will run on the same kernel as the PC and tablet version of Windows, Windows 8, an employee of Vodafone explains.
Peter Becker-Pennrich is a Vodafone chairman, and therefore has regular contact with Microsoft employees. From them he learned that the new generation of the different editions aer running on the same kernel. The kernel provides basic instruction sets and drivers for an operating system. A smartphone running on a kernel that runs on PCs as well is not uncommon. Android uses the Linux kernel which also powers Ubuntu and Linux Mint, for the PC.
Windows Phone 7.5 Mango, the current version of Windows for smartphones, shares no code with Windows 7, the PC version. Windows Phone Mango was presented in October, and is used by many manufacturers, including Samsung, HTC and Nokia. Especially the latter party is very important for Microsoft, because Windows Phone is the main strategy for smartphones for Nokia.
Source: Telecoms.com