Interesting that there's no comment on Weta's work. Or Gollum.

Didn't read the article, but as I understand it this is the exact same technology that was used for Gollum in LOTR, but this time it's being used for the entire movie. That's what's groundbreaking about it.

As I understand it the actors spent the entire film shoot on a 10' x 10' (3m x 3m for the metric fans) area doing "scenes". For some things, like walking down the train corridor, they'd have to start at one end of the box, walk to the other, stop shooting, and repeat. Occasionally they'd have wireframe objects in the shot to give the actors some concept of where things would be. But some of the direction was along the lines of "see that cone? It's a toy. I don't know what kind of toy - just react to it however you want and it'll be filled in later."