While there has been a shift in foreign policy during Bush's second term (one Jim Lindsay and I wrote about here some 9 months ago), it's not so much a shift from unilateralism to multilateralism as it is a shift from relying on the use of force to doing nothing.(Emphasis mine.)
It was this combination of unilateralism, preemptive force, and regime change that made Bush's foreign policy revolutionary.
I hate to say it, but Daalder is wrong. Far from being "revolutionary," Bush™'s foreign policy has been America's standard practice for nearly two centuries. Almost every war this country has fought, including the Revolutionary War, has flowed from a pretext. Our stated reasons for war are almost always about selling the war to the public. This has held true from as early as the Mexican War onward. Even our involvement in the much-lauded WWII was largely artifice (allowing that the cause was good), owing more to our repeated provocations of Japan than of the actual (anticipated) Pearl Harbor attack.
No, the difference between Bush™'s foreign policy and the policies of previous administrations has nothing to do with the use of "preemptive military force" but instead with brazenness. Bush™ does what the West has always done; he just doesn't care what others think of it and his attempts to cover up his real agenda are so laughable that it's a wonder that by now the GOP hasn't imploded. That they have not owes an America-sized debt to the power and efficiency of the Republican propaganda machine and the suckers who haven't yet caught on to the lie.