While I might characterize WikiAnswers as less a search engine and more a directory of Q&A, there is a strong aspect of search that has been improved in recent weeks.
One of the unique things about WikiAnswers is that it utilizes the wiki format, creating a new page for every new question – unless the question is asked again, in which case you’ll get directed to the existing page. From there you can get the answer and add on to it if you know any more information.
Using smart language technology, the site searches its listing of Q&A to find questions that closely match what you’ve asked. If there is no exact match (which might even be the same question in different words) then you get a list of close matches. You can choose one of them as your question or ask your question separately.
So perhaps WikiAnswers may be viewed as a search engine of sorts – a self-growing search engine, that can only get better and better as you ask and answer more and more questions.