I downloaded and installed the MT 4 beta - which now has a version licensed under GPL.

The UI on the system is much more "application-like" - functionality that I used to navigate to are now appearing in dropdowns and many options are saved via XHR. Unfortunately there is nothing new in terms of providing more built-in metadata, but I expect this to change as RDFa and microformats evolve and proliferate.

The new widgets manager looks very interesting - I can't find docs on it yet but it looks like a better way to organize the sorts of public-facing content and functionality that usually appear in the right nav. So MT is now DRYer.

Congrats to the folks at SixApart!