By Monica E. Oss Comparison shopping, common in every other field, has been a long time coming to health care. But recent news from the Centers for Medicare & Medicaid Services (CMS) may signal a sea change in price transparency. Last month, CMS issued a proposed rule that requires hospitals to post their standard charges online (see Medicare To Require Hospitals To Post Standard Charges Online). If this sounds familiar, that's because CMS already "requires" this, but currently allows hospitals an alternative. Hospital can elect to only show the charges by request, as long as the facility posts notices explaining this policy. If finalized,…