I have learned through this forum that Google has an update every three months or so. What is it about this update that gets people so excited? Is it simply an update for PR or does Google reconfigure the entire SERP for keywords? Also, I have noticed that my SERP changes slightly from day to day using the same keywords. How long after I make a significant change to my site (for example a change in sites title) will it take for Google to notice this change? In other words, how can you tell which changes you make to your site are working well or not so well?
The update every few months is normally to update your PR number. People get excited because PR increases the value of your site when selling links or when selling the site itself. If you do neither, it really does not mean much. The SERPs update much more often and to be all honest, no one but Google can tell you for sure what changes you make changes your placement in the SERPs. Basically you just have to track what you do and how it changes things. Age, relevant, content, PR(slightly), and title are all important factors in the SERPs.
As allout has said, the main excitement here comes from the PR update. The constant changing of the SERPs is, in my opinion, much more important that the PR. Alex