AllTheWeb search engine that Yahoo acquired back in 2003 to help build Yahoo Search, will be sunsetting on April 4, 2011. After April 4th, when you try to access AllTheWeb, you will be redirected to Yahoo Search's home page.
A message posted on the AllTheWeb.com reads:
Yahoo! will be closing AlltheWeb on April 4, 2011, as we focus on other features to improve your search experience. Starting on April 4, 2011, http://www.alltheweb.com will redirect to Yahoo! Search at http://search.yahoo.com. Thanks for your understanding.
A Yahoo documented was leaked containing the products Yahoo will be sunsetting. Those products include search engines Yahoo acquired AllTheWeb and AltaVista, however, Inktomi and Overture are currently redirected to other Yahoo properties.