Google's Search Engine Caffeine is Ready for Prime Time
Software Engineer Carrie Grimes wrote on the Official Google Blog that the decision was made to create a new system because of the exponential growth and breadth of new content on the web. Grimes stated that "In addition, people's expectations for search are higher than they used to be. Searchers want to find the latest relevant content and publishers expect to be found the instant they publish."
Google also believes that Caffeine will make it easier to annotate web documents with metadata. As an example, a tweet on Twitter could have additional data that includes the location the post was created.