Whoa, I just found an awesome game played by Carlsen, plus a decent video explanation to boot!
Here's the game:
And the video: http://www.youtube.com/watch?v=ut8IBHa_OGk
I might come back and add in annotations to the game based on what the kibitzer said, but our focus at the moment is on the critical idea of undermining ...c4.
At 0:57 in the video, the kibitzer explains that when black creates a pawn chain with ...a6, ...b5, and ...c4, white can undermine it with a4. I definitely agree, but let's face it: a4 is actually undermining black's pawns on a6 and b5, with little to do with black's c4 pawn whatsoever! If black simply doesn't play along with a6 and b5, what is white to do? I hope to look more into this, but if anyone knows the answer, please share!
At a glance, 4. c3 announces a couple of things. First, it provides an escape for the bishop after a6 and b5, just as in the Spanish. Secondly, it prepares a d4 push, with the idea of exchanging c-pawns with black on d4.
I have little prior knowledge of 4. c3, so I'll start this thread off with one of the example games from Palliser's book.
In summary, Palliser is trying to tell us that ...c4 is a pain in the ass that locks down d4. The above game demonstrates one attempt to kill off the pawn with a tactic, but black executes a solid punishment by capitalizing his light-square control. The moral of the story from is that if you want to play 4. c3, your plans will revolve around overcoming black's nuisance on c5.
This is not to say 4. c3 is a bad move. Frankly, I am skeptical that white cannot have good results with it. More example games should help!