This is more than a mere search-engine query. The Google Search app lets you find things using your voice, search for specific terms of interest in your general vicinity and launch mobile versions of most of Google's other services. The built-in Google Goggles technology is the most impressive feature: it lets you take photos of things like landmarks, buildings and books to get more information about them. It translates foreign text on signs and billboards too.
See also: Bing, Yahoo! Search