Camera.WorldToScreenPoint

function WorldToScreenPoint (position : Vector3) : Vector3

Description

Transforms position from world space into screen space.

Screenspace is defined in pixels. The bottom-left of the screen is (0,0); the right-top is (pixelWidth,pixelHeight). The z position is in world units from the camera.

JavaScript
var target : Transform;

function Update () {
var screenPos : Vector3 = camera.WorldToScreenPoint (target.position);
print ("target is " + screenPos.x + " pixels from the left");
}