Matt posts a quickie to inform the masses that the Caffeine Update is not, directly, a SERP change, but more of an update to the chassis of Google Work.
Although, there may be some SERP changes; so you should check ’em out at http://www2.sandbox.google.com/.
Matt Cutts: Gadgets, Google, and SEO
More info on the Caffeine Update
August 10, 2009