search-engines-web, at our forums, has posted a thread that is quiet useful named Search Engine Optimization Top 50 SERPs since 2004. The thread links to his Google Alert Summary of the top 50 search results for the keyword term, Search Engine Optimization, at Google, since April 2004. He said the report is about 90% accurate. It is always interesting to see how some popular, and/or competitive terms shift at Google over the long run.
Forum discussion at Search Engine Roundtable Forums.