As you are aware, Windows Mobile 6 recently started shipping.  Since Windows CE 6 became available last fall, we assumed that Windows Mobile 6 was built on top of Windows CE 6.0, in the same way that Windows Mobile 5 is built on CE 5.0, and PocketPC 2003 SE was built on CE4.2.  However, this turns out not to be the case.  According to the Windows CE Team Blog, Windows Mobile 6 does not run on Windows CE 6, but rather on CE 5.02.

This will certainly cause confusion with device manufacturers who support both Windows Mobile and Windows CE.  Will they release Windows Mobile 6 and CE 5 devices together, or Windows Mobile 6 and CE 6?  Will they be willing to support two different underlying operating systems?