Search Engines for Wiki Content
Wiki content changes very rapidly, even more frequently than blog sites. However, RSS notification services of page changes only began to appear in 2004. Beyond the problem of getting wikis to make it standard to send notifications of page changes, another part of the problem is volume. The volume of change in high volume wikis has been too great for global search systems to stay current. However, constructing a localized search engine is within the ability of many programmers.
General purpose wiki search engine http://www.wikia.com/
Search just wikipedia http://www.wikiwax.com/
Computer Programming Making a Wiki Search Engine