There is a heck of a rumor that Google is interested in buying Twitter. In an era with lots of talk but no deals (MSFT-YHOO, IBM-SUN) I am not sure if this deal will pull through but WHY would Google want to buy Twitter?
News-as-it-happens is the answer. Twitter is great for searching for what is happening NOW. You feel an earthquake, hear an explosion or want to know if your favourite team scored? Changes are that a search on Twitter will give you results, Google takes a couple of hours to aggregate results.
People want as-it-happens search results and Google wants to deliver. Whether they buy Twitter or not, expect this feature to show up sometime this year.