This ruling [Massachusetts v. EPA] should herald the beginning of a carbon-constrained U.S. economy.
For guidance on which to base a policy [on how to regulate greenhouse gas tailpipe emissions], we can look to the results from the last time the Clean Air Act was amended, in 1990. Those amendments required substantial reductions in the emissions of sulfur dioxide (SO2), the primary component of acid rain. There was broad agreement that acid rain was seriously damaging our environment. There was less unanimity about the method to be used to achieve the reduction in emissions - a market-based cap-and-trade system.
Cap-and-trade works for free marketeers and pro-regulation environmentalists, and actually creates incentives to reduce pollutants. Everyone wins, especially companies who innovate.
There will be a renewed push in Congress to create such a program to force the EPA's plan. McCain and Lieberman have a bill that would do just that, not just for car tailpipes, but all carbon dioxide emissions (like coal-fire electric power plants, oil refineries, etc.) With Democrats now in control, I would assume that a version of this bill will come out of EPW committee in the Senate and the House's select committee on Global Warming or Energy and Commerce committee.
Moderate Republicans, ex-Democrats (Joe Lieberman) and Democrats can form a working majority and pass this bill.