On May 17th we reported on recent Major Google SERP Movement Detected. On May 20th, WebmasterWorld named the update Bourbon and split off the thread into its own. Why Bourbon? Since the upcoming WebmasterWorld conference will be in New Orleans, why not name it after the famous Bourbon Street in New Orleans.
For more information about this update visit Google Update Bourbon - real deal where people are reporting the Google Sandbox being "busted". I see cases of that, on some level, which is a good start by Google.