Championed by Brink Lindsey and Will Wilkinson, liberaltarianism is an attempt by a few libertarian intellectuals to create a "progressive fusionism" within the American center-left and to bring the center-left more in line with free market principles. But it seems like more of a rationalization for affiliating with secular, cosmopolitan liberals even when alliances with conservatives (even if those alliances might be wary and conditional) might make more sense.
This doesn't seem like a great time for libertarians to seek an alliance with the liberals on economic issues. Liberals just gave us a corporatist health care plan that is bound to be unstable and with the next step from the left of center being a single-payer plan. The cap and trade plan would corrupt our energy sector (more so!) and move energy policy in a more statist direction and our spending commitments are unsustainable even as a new entitlement was added amid both record deficits and an impending fiscal pinch. It is difficult to see what the center-left political coalition has, at the moment, to offer libertarians on the economy - aside from a slice of power.
Liberaltarians might argue that liberals are educable on the economy - and they might be right to a point. Liberaltarians could point out that much of liberal opinion has moved more in the direction of supporting charter schools and merit pay for teachers. That is true, but it is also true that liberaltarians had little to do with it. The liberal upper middle-class technocratic opinion on teachers can be seen in shows like the West Wing where the first season focused on hiring new teachers and the last season focused on a pre-Obama candidate who wanted to fire bad teachers. An even better example of a place where the left-of-center has moved in a more libertarian direction would be on the Second Amendment. Even with a Democratic President and Democratic congressional supermajorities, there is no movement to expand gun bans. But once again, our liberaltarian friends had nothing to do with it. The libertarian (or as many would call it rightwards) movement of Second Amendment politics had much more to do with election results in rural and suburban areas and the appointment of right-leaning Supreme Court justices. The center-left political coalition repositioned itself in response not to liberaltarian arguments, but in response to gains by the center-right coalition.
You would think that liberaltarian intellectuals would take their allies where they found them. That might mean allying with the center-right on opposing Obamacare (and working with the more creative conservative free market-oriented thinkers on alternatives) and working with a different (but partly overlapping) coalition on gay marriage. But that might sometimes mean associating with those horrible tea people with their God, overt patriotism and general trashiness and that just won't do. The trajectory of liberaltarianism is to respond to the imposition of across-the-board wage and price controls with liberaltarians patting themselves on the back because they got their liberal senior partners to institute merit pay for park rangers.