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Yes, scrapers should be suffering, but apparently Panda does not catch them all right away. The various incarnations of Panda (it is a constantly evolving part of Google's way of doing things, and not just the "big one" back in February) do target poor quality and one would assume unoriginal content.

I happen to have faith that scrapers and other spam sites will eventually get struck down, but if you are less of a believer you could try filing a DMCA report for particular instances of scraped content: http://www.google.com/support/bin/static.py?page=ts.cs&ts=1114905

Another "me too" here. I wouldn't worry about it, though. "Roger" is usually quick to respond to stuff like this.

Clicked on Campaigns and submitted the error report.

If most of your posts have the same tags and categories, your tag and category archives will look a lot each other and look like your main page which could lead to duplicate content issues.  Many people choose either tags or categories to be indexed and the other blocked. If you can make your tag or category archive pages excerpt only, they will be good for navigation and not be as likely to look like duplicates.  Like EGOL said, category pages can be a pretty big draw - especially when they are full of excerpts that are keyword-rich.