Halakh is VERY explicit on the treatment of workers. Alot has been made of Devarim 24:12, but verses 14 and 15 also are relevant, as I am sure many other passages, as well as interpretations from important Rabbyim from Hillel and Shammai to the present day.
I don't know that this is explicit in Jewish (although it is certainly implicit), but it is very explicit in US law.
I am disappointed in the calls around the country to boycott Agriprocessors. Suppose a boycott were to succeed? Would the company be able to recover from it? How would that effect the short term availability of glatt meat?
Now that being said, the Jewish Star has reported, and the Orthodox Union appears to have affirmed, that Sholom Rubashkin will step down from the leadership of Rubashkin's after a search for a new CEO concludes. I am hearted that the Orthodox Union is pursuing this approach. Likewise, I would hope this change will be a healthy one for the company -- many a company did well with it's founders, but as it prospered and matured, those founders often had to step back from their roles in order for the company to flourish. I hope that a new team there brings greater success to Agriprocessors and it's employees.