If a fiscal-cliff deal gets made, chances are it'll include some concessions along those lines. Obama's opening offer to Republicans included $400 billion in deficit reduction from unspecified changes to entitlements. Suzy Khimm has a helpful rundown of what entitlement changes Democrats have signaled a willingness to consider.

Thus far, defenders of Social Security have been gratified to hear White House Press Secretary Jay Carney say changes to the program are off limits in the negotiations, and even the $400 billion in the president's offer isn't too alarming -- that savings could come from reducing payments to pharmaceutical companies rather than changing eligibility or benefits, says Jeff Hauser, spokesman for the AFL-CIO, which has been campaigning hard against entitlement-benefit cuts. "Our red lines continue to be clear: December 31 should be the last day of the failed Bush tax cuts for the richest 2 percent, and there is no need for middle-class beneficiaries of Social Security, Medicare and Medicaid to contribute to deficit reduction for a deficit they did nothing to cause," Hauser said. But while the group would loudly protest any proposed cuts to benefits, he said, "we are open to improvements in the cost-effectiveness of our health-care system."

2. Elizabeth Warren: The liberal rock-star senator-elect from Massachusetts has the hopes of a movement riding on her shoulders as she prepares to move into the Capitol. Progressives seem to think she'll immediately become a major force in Washington, a triumphant, one-woman populist crusade that will quickly bring the big banks and corporations to their knees. Warren has already reportedly been promised a spot on the Senate Banking Committee, a gesture of respect on the part of Senate leaders for her cachet with the base, despite heavy pressure from Wall Street to keep her off.

But if Warren wants to be a player, she'll shun the limelight and put her nose to the grindstone, Senate veterans say. And those expecting her to shake up the institution are sure to be disappointed. "I understand my friends on the let have some high hopes that senator-elect Elizabeth Warren is going to come in and immediately change the place," said Jim Manley, a former longtime aide to Majority Leader Harry Reid and self-described institutionalist. "The fact is, that's not going to happen. The fact is, the Senate is much larger than any one individual. ... A freshman on the banking committee is on the end of the dais, the last one to speak, the last to question the witnesses. Star power is great, but the only way to affect change in the Senate is studying briefing books, attending hearings, getting to know your colleagues and carefully choosing your spots."

3. Filibuster reform: After years resisting the idea, Reid now says he supports making changes to the Senate rules, which have increasingly been used as a tool of universal obstruction by the minority. (Read David Graham's excellent primer on filibuster reform here.) This has the left, for whom ending the filibuster is a cherished priority, very excited. But "ending the filibuster" is a pipe dream -- any changes that do get made are likely to be minor; the leading candidate is ending procedural filibusters on "motions to proceed," while continuing to allow them on other votes. And while Reid is clearly on board with changing the rules in theory, there's another big question: Would he go as far as to try to change the rules with a simple majority vote on the first day of the Senate session in January, a constitutionally questionable step opponents have called the "nuclear option"? Or is he only willing to try to get it done with 67 votes under normal circumstances? Getting 67 votes for anything controversial in the Senate is a heavy lift.