On 26th September, Pierre Far (a Webmaster Trends Analyst at Google) announced on Google+ the latest Panda update rolling out.
This update is supposed to help Google more accurately identify low-quality (thin) content, and they say it could help higher quality small to medium websites to rank better.
If you saw a drop in traffic around the end of September stretching into the first week of October, Panda 4.1 may be to blame. For a better idea on how Google changes impact your site, I recommend you check out the free Google penalty checker tool.
If you want to see the biggest losers (and the biggest winners) after Panda 4.1, check out this post by SearchMetrics. Their conclusions were as follows:
Biggest Losers: Aggregators – Games sites, lyrics portals, medical sites (presumably with regurgitated or curated content but little in terms of uniquely important content).
Biggest Winners: Quality content sites!
My Panda 4.1 Opinion
My own opinion on Panda 4.1 is that it is nothing new. Google are still asking the same questions about websites, but they seem to be better at answering those questions.
If you want to work out why your own site was hit, I recommend my own book “SEO Checkllist”, which is available on Amazon as Kindle and Paperback:
This book is a comprehensive checklist so you can do your own website autopsy to find problems. It’s the same checklist I use on my own sites, and those of clients.