The Disrupted Library Technology Jester blog has published an excellent comparison of three new search services: Wolfram|Alpha, Microsoft’s Bing, and Google Squared; see http://dltj.org/article/alpha-bing-squared/. Wolfram|Alpha and Google Squared are “fact retrieval” search engines whereas Bing is more like existing search engines that retrieve web links about a topic.
The post features an 8-minute long screencast that contrasts results from the three search engines. I recommend taking the time to watch the screencast; you will come away with a good understanding of the differences between the three services. Note the new service described at the end of the post that provides a way to conduct a search across all three engines.