Google is working on a next generation version of its search engine, currently referred to as "Google Caffeine". Google Caffeine appears to be a pretty substantial overhaul to the backend of Google, primarily affecting how it indexes the internet via changes made to its algorithm. This means that from the visitor perspective, at least at this point, Google will look and feel very similar to how it exists today but the search results returned may be different.
Google Caffeine is described as being faster, more comprehensive, and more accurate with results. You can check out running test searches and queries over at the developer sandbox for Google Caffeine. The sandbox is being refreshed and tweaked frequently, so don't be surprised if results change or the service is not always available.
At the time of this article, there is not a known release date for Google Caffeine. If you want to participate in giving feedback to Google on Google Caffeine, head on over to the developer sandbox version of Google Caffeine and run any test query. On the results page, in the footer area, you will see a link that reads "Dissatisfied? Help us improve" which you can use to communicate your feedback.