This past week, Google rolled out its latest iteration of the Panda update, which the company (as usual) downplays as only one of roughly 500 yearly algorithm changes.

It doesn’t sound like such a big deal when they put it that way, but for those who have lost major traffic because of it, it was a bigger deal than most of those other roughly 499 changes. Ask Dani Horowitz from Daniweb, who noticed the big traffic drop and tipped us about it before we confirmed the update with Google.

Daniweb was hit by Panda earlier this year, and was able to get all the way back to a 110% recovery – something few have been able to achieve. Then along came Panda “2.5” (as the industry is calling it) early in the week and took away more than half of Daniweb’s traffic overnight. All of the hard work that Daniweb put into that recovery might as well have been erased.

But Daniweb is far from being the only victim here. SearchMetrics, which has regularly released data about Panda winners and losers throughout the year, has compiled another list of the top winners and losers as a result of 2.5.

Here are the biggest losers:

A few things worth noticing:

A. Press release distribution sites were hit again. We talked about PRNewsire getting victimized by Panda in the past. Now it, along with BusinessWire – arguably the two top services in this area on the web, have been hit again.

B. EzineArticles and Demand Media’s eHow – two big past Panda victims are not present on the list.

C. Some pretty high profile sites are on the list. Today.com. TheNextWeb (which if anything has increased in quality if you ask me).

It’s a pretty interesing list, as is the winner list:

A few things of note with regards to this list:

1. Google sites won again (YouTube and Android.com). I’m not saying they shouldn’t be on the winners list, but given the regulatory scrutiny Google has found itself in over how it treats its own content in search results, one has to wonder if this will draw the attention of regulators.

2. HubPages is on the winners list. The site, which we have written about several times, used to make the loser list. They must be doing something right. But who knows? They could get hit on the next one. One would have thought at that Daniweb was doing something right too.

3. The list is dominated by pretty big brands.

I’m sure we’ll be digging into all of this more soon, but this is a quick look at what Google’s algorithm is considering to be of quality, for better or worse. It will be interesting to watch how these sites perform moving forward.

I can tell you one thing, Google is all about some identity these days. I’d encourage you to take advantage of the authorship markup Google uses to highlight who is responsible for various content. They’re even starting to include Google+ Circles numbers with it. It’s looking more and more like you ought to be taking full advantage of Google+ if you want to do better in search.