"In this exciting new tutorial we will go beyond basic tracking with a new Video Copilot preset for utilizing corner-pin tracking data. This new preset allows you to create dynamic Null Objects based on corner pin data from Mocha AE. It’s a simple solution to getting precise control over your tracking data and the tutorial shows you all you need to know. The explanation is more complicated than the process!
The preset interpolates a specific point based on your corner-pin data so you can attach elements to an infinite plane of a moving shot to fake depth and parallax; without 3D tracking."
You can find more info and other approaches to Corner Pin effect, tracking & resources, and mocha inside AE Help and via the post tags below.
Update: Andrew Kramer posted an add-on project, Magic Ball Tracking,
"In our recent Magic Tracking Tutorial, we used a new preset to help locate a specific point on a surface tracked with Mocha AE. This technique works well to establish objects onto a specific location like a sign but you can also slide objects on the surface as well. This example shows the ability to animate that point along the surface by keyframing the position of the NULL. For the boulder I used CC Sphere with some fast rotation and manually scaled the ball as it reaches the camera.
You can even download the project and see how I did the other effects as well but I encourage you to check the Magic Tracking tutorial to see how it works. There is no 3D tracking and it was all created within After Effects and tracked with Mocha."