As expected, Jimmy Wales, founder of the Wikipedia, has launched his search engine, named Wikiseek.com. (This is not a search engine by Wikipedia, but it does use Wikipedia's content - sorry, still catching up). All I have seen are negative reviews about the search engines, you can read Danny's huge analysis at Search Engine Land, his conclusion:
In the end, if you want to search Wikipedia, just go to Wikipedia and search there rather than Wikiseek. That seems the better experience. Or search at Google -- it tends to bring up Wikipedia pages all the time for relevant queries.
I have searched through the various discussion forums and honestly did not find much conversation on it. There is a large thread at WebmasterWorld and a very short one at DigitalPoint Forums.
The overall consensus is that it is currently a poor search experience because of the restrictions of only showing results within the wikiepdia community.
I also did notice someone at WebmasterWorld noted that http://wikiseek.com/ returns a 404, they need to 301 that to the www version.
Forum discussion at WebmasterWorld & DigitalPoint Forums.

Comments:
Jojo
01/17/2007 01:16 pm
Jimmy Wales is not behind Wikisearch. Wikisearch is not Wikiasearch. ;-) Danny wrote a good article about Wikisearch.
Jojo
01/17/2007 01:18 pm
Oh, you linked Danny´s article ... then read his second sentence.
Barry Schwartz
01/17/2007 01:30 pm
Sorry, fixed. Still jet lagged, kinda feel like i am in a tunnel...
Len
01/17/2007 06:14 pm
I've been using http://www.futef.com for searches on wikipedia. Better results than wikiseek and also better than the wikipedia search.
Imnotadoctor
01/17/2007 09:53 pm
Yea more ads! I wrote a little about how i think wikisearch = wikisucks over at my blog.
Structured_Web
10/11/2011 12:15 am
We created a website to make it easier to search for information in Wikipedia. Even Wikipedia does not have that ability. Have a look at our about page (scroll down for the Quick Demo): http://goo.gl/f4wKm