Columbia University Professor of Economics and Law Jagdish Bhagwati makes a very clever and innovative argument in favor of the Employee Free Choice Act (EFCA). Essentially, his point is that EFCA is a good way of shielding American workers from the impacts of globalization while not resorting to protectionist measures which would interfere with free trade. Right now, most of our unionized workforce is in manufacturing sectors. Unfortunately, those sectors are the ones most likely to leave our shores.
Fortunately, there is lots of room to organize the service industry, which will be the heavy hitter that takes manufacturing's place once globalization shakes itself out. As Matt Yglesias points out, there is no intrinsic reason that manufacturing is well organized and service jobs aren't, except that the law was far more union friendly back in the days when factories were king. Passing EFCA would give some of the newer, up and coming unions (like the SEIU) a chance to make it so the new jobs created to replace departing manufacturing positions still provide decent compensation and working conditions for working and middle class families. That's a good thing.