it would be quite important in a Public setup of JIRA to have moderation ability. here are the events i'd like to moderate:

• new user accounts. a moderator would need to approve the account before the user can login
• new issue creation. a moderator would need to approve/confirm the issue before it becomes visible to everyone in the User group

this list could go on for pretty much every action a person from the User group could do.

thanks,
mark