The following question was asked by 'Community Wiki'. What does it take to mark question as community wiki'?
Anybody with the right privileges (including the asker/answerer) can mark a question as community wiki.
The idea being that it is a question/answer that would particularly benefit from being kept up to date by everybody then marking it as a wiki entry makes it easier for others to edit, i.e. they don't require the usual level of reputation needed for an edit. It also means that no points are awarded as it's supposed to be a community effort rather than one person leaching points from everybody.
As for this particular question, I think it was automatically marked as a community wiki by the system because of the number of edits made to it. I've now removed that status as this question does not really fit the criteria for being a wiki page.