Yahoo on Thursday unveiled a new beta feature on its Web search that checks to see if there is a single, relevant result to a query and pops up the answer in a "search bubble" using advanced AJAX scripting. For example, weather information or recent news headlines can be displayed instantly without submitting a search.

"Instant Search represents an experience that's different from what most of us expect from a search engine, so it takes a little getting used to. But once you start using it, it's hard to stop," says Instant Search product manager Stephen Hood. "For example, in the past I would typically hit Enter as soon as I finished typing in my search, but after using Instant Search I now find myself pausing to look for the 'bubble'."