  I am not sure that we can easily state that such a law significantly changes the job market. Obviously, the key variable in understanding the problem here is price sensitivity.
It would be interesting to see if there is a noticeable difference in the purchase of plastic bottles in Iowa. If the drop in demand for cans is made up for in the demand for bottles, then what we have essentially done is made a system of wealth transfer from can producers to bottle producers (though I would venture to suggest that they might be the same firms).
While Iowa can claim a 2% raise in recycling (though I might suggest that other factors might have been relevant, such as the rise of a recycling culture), what happens to the people who never claim their money? As David points out, on the aggregate, this is a significant portion of income that is not being spent elsewhere. The rest is obvious. 
