It's almost the Star Trek transporter, it's the astronauts in Houston and in Darmstadt, Germany, training together to repair the Hubble Telescope.

CNN brought in from Chicago holograms of correspondent Jessica Yellin and, later, of Wil.I.Am from the Black Eyed Peas, whose Yes We Can and We Are The Ones videos are celebrations of Barack Obama's message. Each glowed with a full-body-outline of purple light.

Gizmodo explains how they did it: How the CNN Holographic Interview System Works.

It begins with "35 HD cameras pointed at the subject in a ring," so don't expect this to be household tech for a while.

Updated Nov. 6 2008:
Uh, Wolf, That CNN Election Image Wasn't a Hologram

"Blue screen" effects, since the people were only visible on your TV screen; the CNN anchors couldn't see the people they were talking to except on the monitor. They weren't standing before them as they appeared to be.

"The bandwidth that exists with today's technology hardly exists to record that much information," commercial holographer Jason Sapan told CIO Today (the first link).