Application overview:

This attached VS2008 C++ solution illustrates how to programmatically [1] bring up
» the Windows CE desktop,
» the Windows Mobile Today screen,
» the CE 6.0 or WEH 6.5 PsionVU screen.

Such program may become handy in case the device Security Level is set to User è the Desktop option is, as depicted below, greyed-out

& You could use the control panel App Launch Keys applet, to map a key combination to one of the below programs

vvvv

[1] The program source code reads as follows

 

#include <Windows.h>

int APIENTRY WinMain(HINSTANCE hInstance,
                     HINSTANCE hPrevInstance,
                     LPTSTR    lpCmdLine,
                     int       nCmdShow)
{
        SetForegroundWindow(GetDesktopWindow());
        return ERROR_SUCCESS;
 }

-- 

[2] The CE 5.0 variant can be executed against all OS flavors (CE 5.0, CE 6.0, WM 6.x and WEH 6.5)

vvvv

References:
» NEO Security Mode post
» PsionVu and Open TekTerm post