Last updated January 10, 2012.
This section of the Contributing to Documentation pages describes the specific process of how to contribute to writing and editing documentation. Be sure to check the Current Priorities page to learn about the immediate documentation writing and editing priorities of the documentation team.
If you'd instead (or also) like to get involved in special projects, check out the Community Initiatives - Documentation Projects page.
If you'd like to get involved via events, the Documentation team page has a section describing how to participate in and organize events.