A disclaimer up front. I wrote my first outliner in the late 70s, and have been working in this area ever since. I built a huge amount of software around outlining -- a programming language, editor, debugger, database, menu editor, web content management system. I've been writing my blog, Scripting News, in the outliner since its inception, in 1997. All my DaveNet rants were written in the outliner too. I live in the outliner. I'm writing this in the outliner.
Anyway, I have some advice to offer the developers of Workflowy: Simplify your model. I want to be able to see all levels while I'm editing. No need to do all that zooming. It looks nice in demos, but it's non-functional, and limits the fluidity of the tool, esp for reorganization.
Another suggestion is to hook it up to OPML and offer that as a way of sharing. If you do that, it'll immediately hook into the worldoutline software I'm developing. I think there could be some nice synergies. Outliners should work together.
And since my outliner only works in an offline mode, I can give Farhad what he wants there, and you can stick to the online outlining, which is a very good place to provide outlining.
Also, Farhad is a really smart guy. I always stop and read his stuff when it comes out, and have only disagreed with him once. Smart people are the lifeblood of outlining. That's the best thing about making this kind of software is that you get to work with and for such smart people. They are a joy.