A friend made a pun about lack of windows in the incoming Windows Phone 7:
http://twitter.com/marcin_walus/status/27182240050
Funny, because there seem to be none. Also, even in Windows Mobile, the predecessor to WP7, they weren’t really used (the only “window” that I could drag was probably a MessageBox control). However, since the WM was based on Windows CE, which in turn was based (visually) on Windows 95… there are windows there, and you can even move them ;-)
[DllImport("coredll.dll")]
extern private static int MoveWindow(IntPtr hWnd,
int X, int Y, int nWidth, int nHeight, int bRepaint);
While I am sure that similar API is technically present (though not available) on Windows Phone (which is based on Windows CE, too), I have even better answer to the title question:
The phone itself is a window. A window to the world your data:
Image by Stephane Crozatier, http://blogs.msdn.com/b/stephanc/archive/2010/04/04/windows-phone-7-panorama-control-sample.aspx
The suggested UI layout for most applications, called Panorama, shows it very clearly, by offering a seamless – yet modular – view. It would be even cooler, if you could pan or tilt your phone (or move your head, tracked by the ..gulp.. non-existing front-facing camera) to change the “point of view”. But dragging with fingers should do for now.
What’s that? You asked for plural windows? Damn…