A question about Markdown editors with live preview is specific to Mac OS X, but several other answers, including mine, discuss applications that run on other operating systems.

Is it appropriate to edit the original question and broaden its scope from Mac OS X-only to any application that meets the non-OS-specific criteria?

It seems like the broader question should attract more canonical answers that cover the waterfront of Markdown editing options irrespective of OS, which ultimately seems like it will be a more useful artifact to leave behind for others.