Please go through the discussion - http://forums.digitalpoint.com/showthread.php?t=2326618&highlight=google+dance
hi when the website shuffle from one position to another in the page ranking in short span of time , this is know as the google dance .
"google dance" doesn't really exist. It's said that way because more and more uneducated webmasters, who mostly make website without to know a single bit of code, can't remember the word "sandbox". A new site is "sandbosed" by the different google data centers containing discrepencies. That's when G "spiders" are entering in action. Each time the difference between SERP positions is reduced and your site settle to its place depending on your keywords density. Once your site seems "not moving much" any longer, it's been sandboxed. It has nothing to do with post #3 above.
As we all know Google is very giant information based company and for that it needs large database for storing the various data. Time to time these data needs update and for the purpose of refreshing the database Google activates a process of updating the information. That process we all know is Google Dancing and it happens 10 time in a year.
Google Dance is referred to as a period of time , which Google normally takes to rebuild its rankings. And because of this, its results fluctuate for 2-5 days. But that was a thing of past as, these days, Google updates its results every week in order to display effective and better Search Engine results.
Google dance has been used to describe the index update of the google search engine. We will keep this site up running because it provide some informative beyond the google dance.But there will no longer be a monitoring of update data centre during a dance.