The most prominent new feature in Movable Type 3.1 is the dynamic page functionality, allowing you to choose between static page generation or dynamic pages on a per-template basis. This allows you to optimize the performance of your weblog, providing you the best of both worlds…
I understand that this functionality is what they hired Brad Choate for.
The new category management interface in 3.1 gives you fine-grained control over the organization and display of your posts. You can easily create new subcategories, and move a subcategory from one parent category to another using a sleak, intuitive interface.
People have been screaming for subcategories for as long as I’ve been working with MT, and someone made a subcategories plugin for MT3.0, which I believe is Six Apart’s secret strategy for developing the platform.
Using post scheduling, you can set a time and date for your posts to appear, permitting automatic updates to your weblog even when you’re away.
Another huge improvement that people have been using MT-Rebuild to approximate for quite a while now.