@ohno; I've tried with and without adwords. (I used to spend big with adwords so I have known effective campaigns that I can turn on and off at will.) As far as I can tell, my adwords spend doesn't affect the organic traffic, at least in the < 1 month time frame.
@diberry; Point of information: I have a large knowledge base on my site, siloed...but on the same domain. I've been moving that to a subdomain with 301s but only recently finished. Google hasn't fully noticed this yet. Could it be that Google refuses to realize that a domain has both informational and commerce pages?
US, ecom, Panda 1.0 penalized.