Important change
End users can not mark questions wiki anymore, so the only appropriate way to get action on a question you believe really should be wiki, is to flag it for moderator attention.
A couple points..
Vote-to-wiki will not be implemented. When the answer to a problem is "let's make things arbitrarily more complicated", it is rarely the correct answer.
Do not bully users into community wiki. You can offer a carrot in the form of a comment that says "wow, I'd love to vote this up if it was community wiki" but downvoting and other nagging is not appropriate. (addendum: the community wiki flag checkbox is not shown for new users because they can't possibly understand it, you may potentially be nagging new users about a setting they don't even have.)
If you think something should be community wiki then flag it for mod attention with a comment to that effect. Simple.
Also, note that as of now the CW edit threshold has been reduced from 750 rep to 100 rep on all sites.