Windows Phone 7 is on its way :-), and as you might have noticed, a lot of things are changing that will make it difficult to build customized devices such as handheld terminals or ruggedized devices like this one using Windows Phone 7 OS:
As a matter of fact Windows Mobile has been a really attractive solution for handheld terminals manufacturers as it provides a common platform enabling using third party software leveraging the Windows Mobile SDK. And it also allowed customers not to be tied to a single hardware (making it easier to maintain a deployed solution) for running a software solution. Windows Phone 7 will not allow to do this. But be reassured, Windows Embedded is taking over this business and will propose solutions.
Read this post from Dave Wurster, Product Manager in the Windows Embedded group for the Handheld Terminals explaining how this is transitioning from Windows Mobile to Windows Embedded.