The Demo package now includes the Forum found on this site. This is a very lightweight forum that allows you to offer visitors to your site the opportunity to comment and ask questions without having to register. To prevent automated attacks by bots the message form uses a Captcha block, but there's no protection against human abusers so if you need something more robust you should look at a more heavyweight offering.
If you need to be notified of each posting you can set up an email address, subject and sender address - see the Content manager "forum" section. If you leave the email address blank no messages will be sent.