You want Vegas Post for that, which comes out Monday. It can be done in Vegas, however, just not as easily.

Easiest way to generate a shape in Vegas is to add a solid color to a track, then mask it out using either event pan & crop's mask tool or the bezier mask fx plugin until you have the shape you want.

To scale that shape, or move it, or even animate it, adjust the track motion of the track you dropped the solid color onto, which will move the entire track, color, mask, and all, and scale it. You can use keyframes to animate it doing stuff, and also make it drop a shadow in the track motion menu.