Former Bush Medicare administrator Mark McClellan makes an interesting point in Sheryl Gay Stolberg's Times piece this morning:

Whether or not Mr. Obama gets the kind of comprehensive bill he is hoping for, Dr. McClellan said, Congress is all but certain to take up health legislation by early next year to fix a measure that would impose a draconian 21 percent cut in Medicare reimbursements to doctors. And once it is tinkering with health care, he said, it is not that big a leap to imagine lawmakers using that bill to take smaller steps toward expanding coverage and passing insurance market reforms.

“Everybody is talking about how the public is very concerned about some of the specifics that they’ve heard,” Dr. McClellan said. “But the public is also very concerned about some aspects of the health care system, including the cost, including the security of their coverage. So depending on how this plays politically, I think there is the foundation for building support for broader legislation.”

Maybe that's an argument against compromising too much now--since you can probably always come back and pass the less controversial parts of health care reform when you take up those Medicare reimbursements later on.