Interesting. After reading all these replies, I'm now really hyper-aware of the 4th wall aspect to video games. I've been familiar with it in theatre for quite some time, and I am a live improvised comedy theatre actor so I know how easy it is to break the 4th wall. I've always thought of it as something that betrays the intended scope of the fantasy. I think games are interactive fiction by design, so you're supposed to be immersed, but interactively so. It's up to the writers to decide what the rules of the game's fantasy are. There's a difference between a soliloquy in a play, and a moment where the actor starts wise-cracking back to a heckler. One is intended, the other is accidental, and is beyond the scope of the play. Furthermore, i've seen desperate attempts to keep from breaking the 4th wall in improv, like when someone in the audience's cell-phone rings, and the actor mime-answers their cellphone, there, the actor deals with the situation within the reality of the play. It's clear that information is passed through the wall, but this is not really _breaking_ the wall, because it doesn't betray the fantasy, it just draws on information that is exchanged between the fantasy and our reality.
Obviously, the video game is trying to set the scope of the fantasy and the degree to which you are expected to be immersed. If that gets radically changed for some reason in a way that suddenly made the laws of the fantasy world seem changed such that they involved more of our reality that you originally thought, you could say that the 4th wall had been broken, or you could just say that the writers were going for that kind of a twist. This can be a great source of humour. I've seen some cool movies where the characters acknowledge that they're making a movie, and it's done intentionally.
Video game designers are given a hard task of justifying phases of the game like the install, the menu screens, dealing with errors, ending the game and restarting, etc.
One of my favourite goofs is when the in-game character speaks out "I have to hit the X button to pick that up" like my character is holding a game controller?!?...what exactly is the perceived reality in those situations? Sure it's self referential, but I believe that those things are just errors that lead to a less immersed experience for the gamer. A much better line would be "You have to hit your X button if you want me to pick that up." Of course it could just be a stylistic choice by the writers to blur the lines as the article said.
I'd like to see a video game that blurred the lines so much that it made me think it wasn't running. So it integrated with my outlook, blackberry, windows desktop etc. It could do crazy things like call me on my cellphone, send me emails, instant-message me. That would be FREAKY!!! Maybe the game will read slashdot and the in-game character will reference real-world events in-character.