+1. Yes, please! This would be very useful to me and would likely make editorial the app of choice for much of the org-mode community (http://orgmode.org/). The whole org-mode manual is here: http://orgmode.org/manual/index.html
A. ** Simply adding folding based around "*" instead of markdown' "#" (as mentioned by egor) would actually be a HUGE step **(http://orgmode.org/manual/Global-and-local-cycling.html#Global-and-local-cycling).
EDIT: Folding on "*" does work, but it is different from the built in folding. It is more like hiding than folding. That is, the lines disappear, but are not bound to the previous line. So, if one tries to arrange paragraphs there are two lines to move. In contrast, with the built in folding the folded line and previous line are bound together. I would vote for an option for folded text to be bound to previous line.
EDIT #2: Somewhat better folding with * can be achieved using a python script to do it. But it's still less graceful than the built in folding with #.
B. There are a lot of similarities between org-mode and markdown and taskpaper. Some of org-mode is similar to MultiMarkdown (e.g., tables). So you've probably already implemented a lot of the functionality, it's just different grammar.
org-mode uses square brackets slightly differently from markdown. Namely, it uses [#A] and [#B] etc to label priority levels. It uses [[filename]] to link to files. http links are auto-detected.
C. The community could then write a number of workflows to get things done.
D. After folding, color coding of "TODO" (red) versus "DONE" (green) would be high on my list. Users can specify what keywords are available such as "TODO" , "DONE", "WAITING", "STARTED"
http://orgmode.org/manual/TODO-items.html#TODO-items
E. Next I think people would want access to checkboxes, although I'm not big on using those.
http://orgmode.org/manual/Checkboxes.html#Checkboxes
Stoph
