Wolfram Alpha is most of all a scientific initiative and a challenger for Google, providing aggregated data and not a list of sites. The new search engine provides formatted answers to your questions, not only a list of links and you should that Wolfram Alpha has just gone live today.
Stephen Wolfram founded Wolfram Research, that created the world-famous Mathematica (computational app used by mathematicians and scientists). Wolfram Alpha also resulted from the same company and it aims on providing the needed data for people who use the web to search for answers to their questions.
Getting into the details, we learn that the new search engine gathers data relying on your search terms and shows the required answers in a formatted structure (graphs, charts plus many visual aids). For example, if you want more info about the Hubble Space Telescope, you’ll not only get data about it, but also its current position and its launch date.
However, one should keep in mind that the search engine is not 100% ready yet and it can fail to bring up all the information you need, but it is however a challenger for Google, due to the complexity of the displayed info and its neat formatting.