Long time lurker for many years...just thought I'd offer some perspective from what we've seen with this update.
First, our site is an e-Commerce site that actually sells and ships a product. We've been doing this since 2002 and have a strong presence in our industry. Our name recognition is so strong the top three keywords to get to our website is a variation on our company name.
We have had no real link building program, all of our external links are from either satisfied customers or trade types who review our products. The vast majority of products we sell are products we are the sole source for or manufactured ourselves.
What we've seen from this update is about a 7-9% decrease in Google traffic. Sales and revenue is nearly unchanged, but I would say the main reason for that is our brand is so strong that people search for US to buy our widgets, not searching for our widgets.
Perhaps the most annoying thing we've seen however is many keywords for our widgets now have the top 1-5 spots occupied by expired auctions or old sales by our customers on major sites. I know we can't list keywords or links, but we're pretty much the only company with these items in stock, and we've dropped from #1 or #2 down to #5-6 to be replaced by the closed/expired auctions from various major auction/sales sites.
This update has given us some incentive to add Google Rich Snippets to show we have items in stock, price, and ratings. While I don't think it will short-term improve this, I think the logical evolution for E-Commerce SERPs will eventually be factored in by criteria like price and availability.
In the mean time, we would encourage all Webmasters to REPORT SPAM to Google. Our IT department is spending hours looking for it and Google has taken action. I honestly believe they want to have the best possible search results, so lets help them achieve this goal.