Check out some of the new and exciting features in version 3.1:

Improved database routine for better scalability to millions of users/posts.
Pre-moderation: View all posts and approve them before making them live in the forum.
Social Bookmarking links - use these, or add your own to increase site traffic.
Spam/Ban control: Ban by username, IP address or email address.
Censor word list: Imrpoved censor word control.
Support for GoDaddy-style high security shared server installations.
Improved theme and avatar library - easier to make your own themes now!
As always, completely customizable!!
And more!