What is the Google Dance?
Google Dance as defined in the community maintained wikipedia is:
All differences in the Google index on different DataCenters are called by SEO experts ‘GoogleDance’. It simply means that You can get many different results when You just click search or try another machine, browser etc.
Why does Google Dance happen?
The main reason for the Google Dance is a propagation issue. Google has more than 1000+ datacenters around the world. And there are some people dedicated into finding the IP addresses of all Google datacenters.
Although not all Google dances are attributed to propagation. Sometimes these can also be algorithmic in nature. Where some datacenters are testing a new behaviour on how Google will work and they will compare this with the rest of the datacenters to determine which one they believe runs better. The most recent announced algorithmic change was the rollout of the Google Big Daddy datacenters early March 2006.
The Google dance has been popular, but we have also been observing a Yahoo Dance and MSN/Live Dance with the recent SERPs for Ituloy Angsulong.