Not many ecoms were caught in Panda- the big movement was October 2010.
The only ecoms really caught were those who were clearly on an ecom free ride in SERPs. Ecoms get placed higher than an info site would, given the same offsite profile. Some crappy ecoms (with dodgy onsite practices) were benefiting from this boost. Panda took those out- along with some price comparison sites.
Affected ecoms were more keyword stuffers and Hx Abusers, not feed republishers. However, we rewrite, and we got a significant boost.
Added 1) - ecoms and comparison sites with technical problems were also hit.
Added 2) - republishing ecoms might get adversely affected in 2.2 when the anti-scraper componant<--- You know, that thing they screwed up BEFORE Panda gets folded in.