Customers in a handful of Comcast markets might have noticed that the switch on their promised 3D content just got flipped in the past 24 hours or so; viewers were greeted with a short loop of test content at first, but now, they're getting a message pimping coverage of the Masters Tournament that starts later today. We caught this particular message above in Chicago, but folks with HD boxes in San Francisco, Seattle, Portland, Denver, Twin Cities, Philadelphia, Boston, Washington D.C., Atlanta, Miami, and Indianapolis should all have access to the programming. Naturally, you'll need a 3D-compatible set and glasses to enjoy the footage, but be warned: if the ball comes straight at the camera, it's going to be really, really scary for a second.

Update:
Oh, and if you don't have a 3D TV or Comcast service handy, no sweat -- you can still watch it online if you've got the right equipment.