It disconcerts progressives to learn that libertarians enjoy and appreciate Saul Alinsky's Rules for Radicals. For a very long time they have tried to equate the term "progressive" with "radical" - but only sometimes - to try to portray their demands as daring, avant-garde, leading edge, or in some other way innovative.
For an example of this viewpoint, just peruse any comparison of the Occupy movement and the Tea Party movement that is written by a progressive. Libertarians understand that the two movements, when at their best, are very nearly identical in meaning. The demands of those Occupiers that are less appealing to libertarians are the same demands progressives have been making for decades, and are considered "revolutionary" by the progressives commenting on the Occupy movement.
From a progressive point of view Saul Alinsky is supposed to be "left" and libertarians are supposed to be "right," whatever those terms mean. Plus libertarians support capitalism, therefore libertarians "can't be radical," ignoring the many and profound differences between corporatism and capitalism.
This must be made clear: the twentieth century was the century of government. That means advocating government is advocating what currently exists. That means there is nothing radical about seeking governmental solutions to society’s problems.
Everything that the progressive has to offer is a governmental solution to society's problems. Their only defense of that single track argument is to engage in the fallacy that if the government is not acting then nobody is acting to solve those problems.
The radical wants something different from the status quo. The conservative is comfortable with the status quo. The political and economic situation of the United States is a mix of mercantilist and Keynesian economics with a near-limitless government. The status quo is "progressive," and that means progressives are not only conservatives, they are arch-conservatives.
The real radical doesn't support more of the same. There are real radicals in both the Occupy movement and the Tea Party movement. Anyone who claims that one is good and the other bad is in support of "keep them divided" and thus in support of the 1% of the population that is composed of elected and appointed government officials with actual power - the real ruling class. The real danger is that the radicals in each movement might discover a common cause with each other.