Some aspects of participatory economics seem to me to have been anticipated in varying degrees. The idea of a bargaining relationship between worker councils and consumer councils, for example, is found in guild socialism, as in G.D.H. Cole's "Guild Socialism Restated". The idea of a distinction between councils for worker self-management and directly democratic bodies for consumption proposals is also an integral part of the May 1936 Zaragosa program of the Spanish anarchosyndicalist union federation. The "free municipalities" were to play the consumption decision-making role, with the "industrial federations" running industries.
The idea of "balanced jobs" was never really developed in the syndicalist movement, I think, despite the syndicalist emphasis on worker empowerment. It was discussed a bit in Pannekoek's "Workers Councils".
Harry Braverman once described a scenario for the auto industry in which this concept would be carried out by educating the entire workforce in science-based engineering, so it would be carried on sort of like an industrial equivalent of a craft collective.
But the part of parecon that I think is most innovative is Albert & Hahnel's conception of participatory planning, & the idea of drawing out preference rankings for work and consumption through a system of proposals and counter- proposals.
One thing I would add to Michael's discussion is the application of the concepts to the process of class struggle itself. If a post-capitalist economic system is supposed to be prefigured in the movement that creates it, then we would need to see the emergence of mass organizations that worked on the basis of rank and file self-management, and in which there were various practices of sharing knowledge and skills, skill development in rank and file participants -- anti-coordinatorist practices, practices that prefigure job balancing and economic self-management.
Tom Wetzel