Last week the federal government announced it had signed up 27 hospital and doctor groups to participate as accountable care organizations, one of the health reform law's great cost-saving hopes.

The number is well under federal projections from October, which predicted up to 270 groups would sign up to become Medicare accountable care organizations, or ACOs. The ACO program pays bonuses to doctor and hospital groups if they successfully coordinate care and improve health outcomes for certain Medicare patients. The groups can eventually lose money from the federal government if they don't meet those standards.

Does the low turnout mean ACOs are over? Or is the program just off to a slow start? Why?