From an AP review (dated May 13) of WolframAlpha by Brian Bergstein:
What's that, you say? We already have such a service?
Well, for all the fears that Google is making us stupid by making it too easy to look up information, at least Google and its rivals enable the critical thinking that comes from scoping out multiple sources.
Unlike search engines that deliver links that match keywords in your query, WolframAlpha is more of a black box. If you have it perform a calculation, it gives you an answer, along with a small link for "source information." Open that and you'll generally be told the data was "curated"—found and verified—by the company behind WolframAlpha. In other words, "trust us."
The site does suggest ways to track down similar information from other sources, including government statistics, proprietary databases, almanacs and the collaborative encyclopedia Wikipedia. To confirm WolframAlpha's data I went a suddenly old-fashioned route—through Web searches on Google and Yahoo. I didn't find any errors, but taking that step made me wonder why I didn't just use Google or Yahoo to begin with.
Rory Litwin has posted similar comments at Library Juice: Wolfram Alpha: Bad Idea!