Microsoft confirmed that WP7 is based on the wince 7 Kernel

Microsoft has not officially published the kernel version of Windows Phone 7 since its launch. A Microsoft Windows CE employee confirmed this in his blog. Windows Phone 7 is based on Windows CE 7 (Windows Embedded compact 7) kernel.

Some sites once thought that Windows Phone 7 was based on WinCE 6. Of course, Windows Mobile 6.x is based on the kernel of Windows CE 5, so for Windows Phone 7, what they think is the turn of Windows CE 6. However, Windows Phone 7 should be compatible with Windows CE 7.

A Microsoft Windows CE employee confirmed this in his blog. Windows Phone 7 is based on Windows CE 7 (Windows Embedded compact 7) kernel.