Is there any good Markdown Javascript library or control?

We've been pretty happy with WMD. There are a few niggling bugs in it, however. Nothing major, but I would love if John Fraser (the author) made the code open source so we can fix some of them. He's promised to do so but other real life projects are getting in the way.

I do follow up with John every week. I'll post on the blog once the WMD source is finally available. Haven't been able to contact John Fraser in over a year now.

We have open sourced both the JavaScript Markdown library

http://code.google.com/p/pagedown/

and the server-side C# Markdown library

http://code.google.com/p/markdownsharp/

If you're not averse to using Ajax to generate the live preview, then another option is markItUp!. markItUp! is a universal markup-editor, and very flexible. It does provide an easy way of creating a markup editor, but unlike WMD, it doesn't provide its own live preview.

I used markItUp!, along with a simple JSP (using MarkdownJ) for one of my open-source projects (a Markdown plugin for Roller). If you're using another server-side technology, replace that simple JSP as appropriate.

I actually starting using this before I came across WMD. I'd agree, WMD is great, but has only just been open-sourced and is, at this stage, more difficult to customize the behavior of.