maybe reading the article would help you finding the answer.
small hint: it's about "cross platforming" other games like "Borderlands, Crysis 2 and of course Call Of Duty: Black Ops."

yeah yeah keep dreaming.

Portal 2 is alright with pads and m/kb playing at the same time, but don't even think about playing COD or BF with players on PC, you would cry all the tears you could.

Seriously, while it's technologically possible, I don't think it will happen again, except if it's a valve made game with some kind of slow place.

ardivt,
I read the article. From reading it, it seems that the way Portal will change gaming forever is by implementing a cross platforming feature that already existed in previous games like Shadowrun (that the article itself mentions).

I don't know - it seems like fail logic to me. If other games adopt cross platforming (something which is purely speculative), shouldn't the "changed gaming forver" be attributed to the game that actually pioneered this?

As humbleopinion said above, Portal 2 isn't the first title to do so..
Shadowrun did cross-platform multiplayer before even Portal was around.
However, as far as being 'done very successfully' maybe Portal 2 did so.

Regardless, it would be neat for more games to implement this feature.

I disagree with that comment. It's not necessarily the game play that sets Portal 2 ahead of the pack it's the narrative and the way it goes about things.

Rather than holding your hand with a big compass saying GO HERE and telling you exactly what to do Portal 2 leaves you to your own devices. It gives you all the tools to complete the challenge, and lets you work out the rest your own way.

Some of the puzzles you will breeze through, others you will sit there forever trying to work it out and then when you finally do, feel like an idiot as the answer was staring you in the face.

Each puzzle has a sense of accomplishment as you complete it, something many other games simply lack.

As for the comedic value, it's worthy of a purchase just for the dialogue.

Adventure games have been doing that for years so nothing new here.