Whenever I’m at trade shows, run seminars, or speak at symposiums I am asked the question “what is the Google dance?” I’ve heard a few different theories regarding “the Google Dance”, but only one is really correct. It’s the period when Google is rebuilding its rankings, and results fluctuate widely for a 3 to 5 day period.
http://www.searchguild.com/articles/article_2003_05_10_1248.html
http://www.google.com/googledance2002/ – the real one!