What I would say (and Tyler seems to be saying) is that libertarians currently lack a rallying point. From the 1930's through the Nixon Administration price controls, the forces of central planning were on the march, and libertarians had an important mission to fight them. But that fight has been won.
Starting with the Carter Administration, deregulation reigned in transportation, communications, and--eventually--energy. These victories for market-oriented policies stimulated growth and allowed us to have the luxury of an enlarged welfare state without crippling the economy. Meanwhile, the trend on social issues since World War II has been mainly libertarian.
For libertarians, I think it is going to be difficult to try to tell the average American that he or she is less free than her predecessors and what we need is radical downsizing of government. It is comparable to the Left trying to tell the average American that the economy has gone downhill since the 1970's, and what we need is stronger labor unions.
Brian Doherty's Radicals for Capitalism is the book-of-the-month for March. (Does anyone have a suggestion for April? It might be nice to get a book-club discussion going on this blog and perhaps others.) He cites Milton Friedman's view that libertarian policies are adopted when politicians get desperate--as Nixon became desperate to reduce the adverse reaction to Vietnam and became willing to abolish the draft.
For libertarians, the problem is that American politics is in equilibrium. In spite of the welfare state, the private sector is vibrant. In spite of the nanny state, people are a lot more free in the dimensions that they care about.
The Left is mostly a paper tiger at this point, as symbolized by the "nonbinding resolution" that they passed on Iraq. Kyoto and its successors are likely to be nonbinding resolutions. I expect a nonbinding-resolution approach to single-payer health care--I'm betting that the Left prefers whining about our health care system to taking responsibility for it.
Libertarianism's crisis is that there is no crisis.