Google has been in the process the last few days of updating. The "Brandy" update shows a slight change in algorithms.
Googleguy, who is the resident Google employee and contributor at Webmaster World says "I usually say change instead of update; it's a little more generic but more accurate, if that's possible." Ok, Google isn't fond of the word "update" whenever they update.
You can always sense the changes coming and supposedly there have been some toolbar rank adjustments felt already. At Blogger Forum today, Google spidered 6.3 megabytes which is higher than normal.