Building a wiki application?
Make sure that good content is not ruined = version each edit and allow roll-backs.  
Check for quality = get people to help with that
Prevent spam from invading the site = get people to help with that, require login, add a captcha if need be, use nofollow for all links
I'm building this app in Python with Django.
I would like to give parts of the site wiki like functionality,
but I don't know how to go on about reliability and security.

Make sure that good content is not ruined
Check for quality
Prevent spam from invading the site

The items requiring wiki like functionality are just a few: a couple of text fields. 

Can anyone help on this one?
Would be very much appreciated. :)