Seeing how the stock of topics is rather meager at the moment and how I thought that rather than saying something spiteful on the topic of linkbuilding via commentspam for large brand-customers in the insurance- and shoppicsector or on the state in which an ominous SEO-scene is in general, the evergreen of SEO-subjects would be more suitable: PageRank, or rather the changes therein. At the moment there are three reasons why the PageRank, for a URL, which is shown through the Google-toolbar, changes:

PageRank-update
Google exports the internally used PageRank to the datacenters in, by now, quite regular intervals and is therefore responsible for the notorious PageRank-updates. The last time that this happened was on 09.27, before that on 07.27 and 04.29 – which means that the odds are in favor of us seeing another update before new years. In general there will be no change in the ranking after a PageRank-update. The “new” numbers were known to Google for quite a time and were already integrated in the ranking. One point that is quite interesting is the reliable detection of PageRank-updates. For this you take a clean site that is a little older that is regularly publishing new articles. Blogs like this one here are especially suitable for this. Then you go back through the articles until you find the last one that still had PageRank during the update. As luck would have it, for me that is the posting about Bernd Sonnensegel. The content which comes right behind it chronologically (this one), is currently shown with a gray bar in the toolbar, which means that it is without a PR-value (for these the German blog postings are used as the translated ones are both without a PR-value at the moment). If we get a PageRank-update, this value will change to at least a PR of 0.

PageRank-adjustment
Besides these large updates there are a number of smaller adjustments of PageRank for single sites and domains. This can happen if Google detects a 301-redirect, if a domain is unreachable for a longer period of time or if they detect two URLs to be identical in content (e.g. www.domain.tld/ and www.domain.tld/index.html). As we can see in the graph on the right, this does not happen that seldom. The graph shows us how many percent of the domains that are monitored by the SISTRIX toolbox suffer changes in the startpage-PageRank. If we compare these changes to a “real” PageRank-update (diagram for 90 days) we will certainly make out a much lower rate of change, but a change all the same. As a result you have forum posts that are shouting “update” to soon, even though there are no new value, just an adjustment of already existing ones.

PageRank-depreciation
The third reason is the detection of linkpurchases, linktrade or other demeanor related to linking which does not suit Google. For about a year now, Google is at work to deprive such sites of part of their displayed PageRank. At the moment the “penalized” site does not suffer any consequences and even the realization itself shows some interesting loopholes (A vs B), which leads us to conclude that Google themselves are not taking this too seriously. Right now we can assume that these depreciations are done purely manual, however I was able to observe some interesting values within the last few weeks which led me to assume that Google is also trying out other approaches.