Wolfram Alpha was released recently, and by all accounts it's a great tool. Groklaw breaks down the terms of service of Wolfram Alpha, and it's a good read for those interested in both search and journalism. The short version: WA claims copyright over search results, and requires attribution. Failure to attribute WA as a source could possibly be "academic plagiarism or a violation of copyright law." The full Terms of Service are worth a read; the above quotation is pulled from the Attribution and Licensing section.
This reminds me of the efforts by some news outlets to control how people link to content. Wolfram Alpha claims to be "an authoritative source of information," and that the process of "gather(ing), compar(ing), contrast(ing), and confirm(ing) data from multiple external sources" gives it copyright over its responses to questions." (from WA Terms of Service -- Attribution and Licensing).
Given that some WA results will likely use data pulled from news outlets and other copyrighted sources, it will be interesting to see where this leads.