Someone asked how often in our experience the SERPS updates appear to come along.
There is a record of these in various sites and it looks like about every 3 months, which makes us on for the next update now (last one was May) There was also a major PR update about a month ago.
GoogleGuy posted in this discussion that there would probably be a PR / Back Links update between now and December. I have to say I find that a bit vague GoogleGuy. I really apreciate your posts here but that one is not exactly revealing, and was correctly followed by the question - "but what about the SERPS?" Considering that we have had a major PR update recently it is the logical next step, and if I'm not mistaken its part of the cycle Google is following.
Now I will speculate a bit...most business don't change their processes continually but establish a routine or pattern that they follow. Indeed they have certain people who perform certain roles, with certain consequences. So we might for example see a process like this for Google:
1 - review the SERPS looking for weaknesses and abuse
2 - suggest ways to counter-act these
3 - test some results on one datacenter with a modified algorythm
4 - review results and tweak to improve
5 - deep spider to get the latest picture of the web
6 - apply new algorythm universally (major SERPS update)
7 - review results and apply any tweaks
8 - start updating back links
9 - update PR based on back links and page data
10 - release the supposed PR value to the toolbar, knowing that this only tells half the story
11 - start over from 1
Of course theres a question of chickens and eggs, but you get the idea. In my guess this whole process takes about 3 months, although it may be more complicated now that they have to consider the comercial aspects of the results. I bet theres even a monthly meeting about SERPs. What fun that must be.