Building a wiki application?
Assuming that there will be a community of users you can provide good tools for them to spot problems and easily undo damage. The most important of these is to provide a Recent Changes page that summarizes recent edits. Then each page that can be edited should retain prior versions of the page that can be used to replace any damaging edit. This makes it easier to undo damage than it is to damage things.
Then think about how you are going to handle either locking resources or handling simultaneous edits.
If you can tie edits to users you can provide some administrative functions for undoing all edits by a particular user, and banning that user.
Checking for quality would be tied to the particular data that your application is using.
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. :)