Teasing everyone with a solution to something we MovableType users been hacking around with for awhile, Ben Trott writes:

We envision Text Formatting options as complete, encapsulated formatters, handling both the formatting of structured text and any desired typographical details (smart quotes, etc), analogous to the way in which Textile handles quote education and its own miniature formatting language.

Plugins will be able to easily add new Text Formatting options to the menu on the New/Edit Entry screen.
Yay! Text formatting as a first class feature in MovableType - used in previews, as well as in publishing. No more including plugin tags in every single template ala MTWikiFormatPlugin and friends. Rock on! It's a good thing when hacks I write get outmoded by a more elegant treatment.