This is just a fansy-pants version of blue-screening, nothing "holographic" about it, sadly.
They "just" have a bunch of cameras (35 HD cameras) arrayed around the person "in a room far far away". The thing that makes it different than a standard blue-screening, like you see when the local station does the weather report (before they switched to large plasma screens, anyway), is that a computer monitors the studio camera and calculates the angle that the "hologram" needs to be displayed from. This image is stitched together from the 35 HD feeds and traditional blue-screening techniques are used to combine the "hologram" with the camera feed.
Wolf Blitzer and everyone else in the studio didn't see the "hologram". They acted like they did, just like the person doing the weather acts like they can see the map or whatever.
From a technology point of view, I thought it was really cool, but way overblown - and it annoyed me that they deliberately degraded the cut-out person ("hologram") to make it look more like a Star Wars (or other sci-fi) hologram. I don't know if they could have removed the glowing border completely (edges are always a problem in blue-screening), but the red glowing circle on the floor and the blue-ish tint of the "hologram" was completely unnecessary.
They could have probably made it so that we couldn't even tell that the reporter "far far away" wasn't in the room. Now THAT would have been cool. Instead we got to see a dumbed down version because that was more "sci-fi" like.
Oh well
Also, only 2 of the close to 50 cameras in the CNN studio were actually hooked up to the computer - so only feeds from those two cameras would show the "hologram".
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