The Conversations block lets you add a guestbook type messaging interface to any page on your website. The settings on that block determines how discussions will be displayed and if posts need to be approved before going live.
This page in the Dashboard gives you a centralized location to manage the posts across all Conversations in your site.
You can limit the results by searching for a specific keyword or changing the status of the post from the drop down that defaults to Show All.
More controls including a banned word list are available under Dashboard > System & Settings > Conversations