Sorry the v2 version used Flash that allowed the browser to extend beyond the bounds of its window and take over the desktop. With the new v3 version purely HTML based, the content is bound by what the browser can do.
You can 'simulate' full screen by having a DIV on your site , inserted directly into the body, absolutely positioned at 0,0 and with the width and height of the window. Then load StreetViewPanorama into it. This will allow you to display the panorama across the full browser window, but not beyond.
Marc