It means that for the last 18 months of his Presidency, Bush is going to govern without regard to polls, the interests of the Republican Party, Congress, or the facts on the ground. His last 18 months will be like the preceding 138 months, only more so. He has, to quote Hunter S. Thompson on Nixon, cashed his whole check.
It means that war with Iran is more likely. I have argued that even Bush would not be so crazy as to make war on Iran, a country with far more territory, people and resources than Afghanistan or Iraq, particularly with our armed forces already stretched thin by years of those other two wars. I'd still bet against it happening--but it might be a good idea to start hedging those bets.
It means that nothing serious is going to be done to address the country's mounting problems with energy, health care, the environment, the budget deficit, and immigration until there is a new President and a new Congress. The Libby commutation is just a big Fuck You to Congress, the courts, the law, the CIA, the GOP and, ultimately, the people.
It means that the federal bureaucracy is going to be even more dispirited, dysfunctional and politicized than it is now. It must be pretty depressing to work at EPA, DoJ, the intelligence agencies, and the arts and sciences grantmaking agencies, to name just a few. The commutation signals that decisions that matter in those segments of the bureaucracy are going to be based on the biases of an increasingly isolated band of political overseers rather than on data, law and sound management principles.
In short, it means we are in for a grim year and a half.