Care of a post and analysis by Steve Rubel, a new stand alone search engine for Wikipedia called Wikiseek has been launched by Searchme. The about page on Wikiseek explains why they think it is different:
"The contents of Wikiseek are restricted to Wikipedia pages and only those sites which are referenced within Wikipedia, making it an authoritative source of information less subject to spam and SEO schemes.
Wikiseek utilizes Searchme's category refinement technology, providing suggested search refinements based on user tagging and categorization within Wikipedia, making results more relevant than conventional search engines."
However, while its a nice idea, I don't yet see as Rubel suggests in his analysis that through search Wikipedia will become a threat to Google - you would have to think that Google could create a similar search fairly quickly if they saw value in it. One other observation I have is that while you can search Wikipedia, there is no direct link to the Wikipedia site!
However from an Enterprise 2.0 point of view, this would also be a great search concept for an intranet search where typically the Web approach to search doesn't always quite work.
BTW Talking of Wikipedia and helping humans to search, this reminds me of another story where researchers have developed a program that uses Wikipedia to help search engines make sense of the world in order to improve search results.