I'm sure you looked, but for those who didn't.
http://en.wikipedia.org/wiki/Progressive_movementSo these were the people who fought for true equality and justice for all. Naturally, Glenn Beck is against this kind of thing. It is the general push of refinement, of adapting to the modern age so that we can live this life humanely. Have factories without slaves, work in dangerous conditions with safety precautions, give workers a voice against powerful corporations, assert the right of poor people to exist, keep their property, and live as happy as they can free of oppressive corporate might.
I also associate it with greater social freedom. Gays should have equal rights, women should be able to vote and be paid the same as men doing the same job, blacks should be able to drink from the same drinking fountain and muslims should be able to build community centers.
For all his impotent railing against progressives, he chose a peculiar date and time for his speach. The 47th anniversary of "I have a dream" on the very site of that speach, given by one of the most celebrated progressives in american history.
Beck doesn't like to think too hard about things before he says or does them.