A search engine, when it launches its operation, we compare it with google and treat it as another google clone, but soon it finds a niche.
Like WolframAlpha , bing, hakia, hunch, cuil, Yebol. As it is clear now, most of them has found or slowly finding their niche.
WolframAlpha is certainly not a search engine. it is a computation engine as they say. it provides us with structured data like google squared but wolframAlpha is much more vast and robust. it is the future of search results, how we want our search answers to be. It should also display unstructured results where it can't compute instead of a blank page.
Bing is a decision engine(they say) and is a bit different from google as it provides a snapshot of results after you search which provides ease of use and also its interface is a bit cheeky.
hakia is structuring the web on the subject level and indexing the credible site with the help of editors -some sort of distributed wikipedia powered with search.
hunch theme and motto - promising Yes, implementation wise still it has a long way to go. I am still to find out how to make it work for me.