Yesterday, I asked a prominent health care operative about the Summit. "What I've heard in my world," he said, "is everyone wants to be there and needs to be there and thinks it'll be terrible if they're not there." That health care operative is here. And so are a lot of others. 50 members of Congress. The heads of AHIP, SEIU, the American Hospital Association, Physicians for a National Health Plan, Pfizer, and dozens of others. The full list follows the fold.