Most people don't yet know but for several months now Google Engineers have been working on a large search engine update.
This is apparently not a normal update and could be considered to be a completely new code base driving the organic results in Google.
The codename for this project is called "Google Caffeine" - most likely due to the fact that webmasters will be drinking coffee all night long while watching the serps change!
Google Caffeine is a next generation architectural update to the Google search engine and the importance of this should not be overlooked.
You can view results of Caffeine here -
Google
There is also a tool that will allows for the results to be compared to the current search engine -
Compare Google Caffeine.
There has also been some recent evidence that some kind of update may be taking place right now and it is possible that Google Caffeine may be in the first stages of a roll out.
Since this is such a large change, it is likely that the new update will be rolled out in several stages and it may take a while for search listings to stabilize.
So don't panic if you see some changes in your serps - wait for everything to balance out.
Google Caffeine
Linear Mode
