The 12/4/2011 Forbes describes how, "CMS Tightening the Screws on Unnecessary Procedures in Florida and 10 Other States".
There are more articles such as this one ("The Doctor's Dilemma -- What Is 'Appropriate' Care?") arguing that physicians should abandon "the primacy of patient welfare" in favor of "collectively caring for a defined population within a fixed annual budget."
Of course, what counts as "necessary", "appropriate", or "essential" will be driven by ferocious political lobbying. If you have political "pull", then your favored medical treatments will be considered "necessary"; if you don't, then you're out of luck.
But just don't call the politically-driven granting (or restricting) of "necessary" care, "rationing".