Google Search is improving the predictive powers of "autocomplete," to help you to provide predictions for even more queries. For example, most people who type "w-e-a" are going to search for [weather], so Google can make that prediction.
"Now what we're doing is making predictions based on only part of your search--specifically, the last word or words. While few people have searched for [florida state senate building], many more have searched for [state senate building]. By looking at just the last part of what you've typed into the box, in this case "state senate bui," we can generate a prediction for "building." You'll see a dropdown box below the end of your search with predictions for just that word," explains Google.
As before, to search for the predicted query you simply click the prediction or arrow down and hit enter. The feature can be particularly helpful for long queries, since the query is likely to be more unusual. For e.g., if you're trying to figure out [how many stairs to climb the arc de tri]... now you'll actually get the prediction for "triomphe" (a good thing, too, because there's no way I'd spell that right). Or, if you're looking for an [online store with underwater gad], you can save that extra second while you're shopping for "gadgets."
[Source: Google blog]