Mass Effect - Interview @ The Guardian

The Guardian talks to Greg Zeschuk about Mass Effect in this latest interview.  Here's a bit about hidden elements in dialogue:

When I last saw the game there was a lot of emphasis on the way your character can interrupt another while they are speaking. Is that still a part of the game?

Yes, it's part of the whole influencing process. But it's not a huge part of the game but you can certainly interrupt in certain ways. There's hidden little neat things in the dialogue tree that you can find.