You won't believe what a great surprise Six Apart prepared for us all :)
Have you even imagined a very simple, fully intuitive and quick way to find a new interface design for your Movable Type Web site, to choose the exact layout you like (with whatever number of columns and their positioning in page) and to even be able to update the interface design style live before saying to youself: "Yeah! This is what I want to apply to my Web site!".
Just check out this post:
Movable Type Design Assistant: Styles Live Customization is Here