SteveG says it better than I'd ever be able to.
For my part, I'll just say that I'm definitely going to miss his incredibly intelligent, absolutely hilarious commentary on American life. The first real exposure to Carlin I can recall is on a field trip to Chicago in 8th grade where my roommates and I sat up until 3 or 4 in the morning watching a marathon of Carlin specials on HBO...quite possibly the beginning of my love of stand-up comedy. I had the chance about two years ago to see the master at work at Warner Theater here in DC, and I'm glad that wasn't an opportunity missed. George, we'll miss you.