WMD is a simple, lightweight HTML editor for blog comments, forum
posts, and basic content management. You can add WMD to any textarea
with one line of code. Add live preview with one line more. WMD
works in nearly all modern browsers, and is now completely free to
use. The next release will be open source under an MIT-style license.

This is not a WYSIWYG editor. Writing HTML to look a certain way
can make your text less accessible to blind people, search engines,
mobile users, and feed readers. HTML describes a document's logical
structure -- not its appearance. It just wasn't built for WYSIWYG.

So WMD is something new: a Wysiwym Markdown editor.