The point of the rally was this...
Too often in our society we see people reflected in the news holding rallies, and demonstrations demonizing politicians both on the left and right side of the house calling each other terrorists, nazi's, hitler, etc. They make outlandish claims about how this side is going to destroy America, or that side is going to destroy America. What Stewart and Colbert wanted to do is show that the way America is portrayed on the news is not how we are.
They wanted to show we are not divided, that were are not racists, that we are not in a class warfare, that we do not believe our leaders are Hitler, or Stalin, and that we continue everyday to grind out our existances together... united. This should be common knowledge but unfortunately the waters have been muddied by our 24/7 news media conglomerates trying to fill time slots by injecting fear, and doubt into our minds and why? Because fear gets ratings.
The rally to restore sanity was an effort to re-allign peoples perception of their society to what it actually reflects, and not what the news media wants you to believe it is.