Definitions of Google Dance on the Web:

• An informal term created to explain the phenomenon of frequent shifts in rankings while Google updates its database.
  www.optymise.co.nz/resources/glossary.asp
• Once a month Google updates its entire index of web sites. That is called the Google Dance and can last for a couple of days.
  www.thewebdivision.com/glossary.html
• The Search Engine Google often updates or process updates to its ranking Algorithm and the Google dance defines the process of the update. Google utilizes 9 data centers that will provide different results until the Google dance update completes its recalculations. When the dance completes the Search Engine Results will show new listings and changes in ranking positioning.
  www.intensedevelopment.net/website-design-G.html
• Google’s once a month update of its entire index of websites.
  www.basimos.com/web-marketing/internet-marketing-glossary-g.htm
• Google, Inc. , is a U.S.-based corporation, established in 1998, that manages the Google search engine. Google is headquartered at the "Googleplex" in Mountain View, California, and employs over 3,000 workers. Dr. Eric Schmidt, former CEO of Novell, took over as Google's CEO when co-founder Larry Page stepped down.
  en.wikipedia.org/wiki/Google_dance