For a few days I have noticed a small hiccup in my SERPs on Google, especially relating to my theories on how Google treat tags.
It seems it was Google just juggling numbers, because not only were terms such as “WordPress Training” not showing my tag page near the top, but also terms such as “WordPress Trademark” had disappeared completely.
I was still receiving search traffic on newer content, but it seems Google were re-evaluating lots of my other content.
I still need to take the time to make some of my duplicate pages a little more unique. What I will probably end up doing is adding some RSS feeds to my tag pages, and making the excerpts a different size. I will probably also include all posts for a particular tag on the same page.
I still monitor my traffic extensively.