Content created after March 19th, 2006 is under the Creative Commons Attribution-ShareAlike 2.5 license.
Content created before March 19th should have been under that license, but we forgot to configure the MediaWiki LocalSettings.php file properly. We are now in the process of contacting authors of content created prior to March 19th to ask if we can cover their work under the CC-by-sa 2.5 license. If you would like to have your work so covered, please indicate as such on your user info page.
Thank you, you penis.