Open edit in a wiki is the most radical form of openness.
In Appropedia, pages are generally open edit, so even an anonymous user of the site can click "edit" on a page and change it.
On the positive side:
- This allows more contributions, without the hurdle of registration
- Most anonymous edits are constructive and improve the site
- There is very little spam, as bots are blocked by CAPTCHA and other tools.
On the negative side:
- There is a perception by some that open edit means unreliable. In practice this is not true, although it's always good to improve the content checking and development processes.
Pages are only occasionally kept "closed" (e.g. protected, or with a notice requesting editors to not edit yet).
Protection
Open edit does mean you'll need to put the effort in to make it hard for spammers and vandals (various MediaWiki extensions and settings can help, for example) and to monitor recentchanges.