Treat wiki pages like articles in a journal.
Title
The title of the page should be included in a citation with traditional capitalization and word spacing. Citations will normally include a URL which will repeat the title using wiki's stylized conventions. So you could have "The Internet (somewhere 
)".
Date
Use the "Last Edited" date of the page at the time of citation as publication date. Please include the month and day. We publish daily from a record-keeping point of view.
Author
Wiki's authorship conventions are often contrary to scholarly traditions. One must be careful to not misrepresent wiki authors just to adhere to some other publication's conventions. Cite specific individuals as authors only if they are clearly the original authors of a page. Again, use normal spacing and punctuation for proper names. Consult each author's page for name elements that might be omitted in a wiki name. A page with ambiguous authorship may be cited as anonymous or as from the collective community known as "Wiki".
When one particular comment deserves citation in its own right, and differs in tone and content from the host page, it may be acceptable to extract the comment and associated responses into a separate wiki page. In this case the page name would be the work of the citer, not the cited, which is pretty strange, but not without precedent. For example, the famous article "Gotos Considered Harmful" was written by Dijkstra (Ew Dijkstra) as a letter to CACM and titled by an editor at that publication.
Publication
This wiki and the pages in it are a feature of the Portland Pattern Repository, published by Cunningham & Cunningham, Inc., Portland, Oregon, Ward Cunningham editor and publisher. This is a mouthful and probably isn't all required in a normal citation, especially when a URL is included. But please don't confuse Wiki Wiki Web, which is a technology, with the Portland Pattern Repository, which is a publication.
Examples
[Cunn 99] Cunningham, Ward. Operator Work Selection. Portland Pattern Repository. February 26, 1999. <c2.com >.
[Wiki 99c] Anonymous. Extreme Programming Roadmap. Portland Pattern Repository. June 3, 1999. <c2.com >.
See original on c2.com