Latest release of Novelang available here.
Just introduced unlimited level depth. There was no special need for this feature: depth of 2 is enough most of time. As Linus Torvalds said: "More than than 3 levels of indentation means you're screwed". But while developing embedded lists I found that a generic way to handle levels was removing an ambiguity.
Please note that built-in stylesheets don't handle a depth greater than 2 for now.