I have added markdown support to a meta field in a custom plugin using the suggestion here.
WPCom_Markdown::get_instance()->transform( $content )
This works fine with the exception of paragraphs (I understand these are inserted by inserting two or more spaces and pressing return).
In the above example, $content is simply the contents of a post meta field collected from a text area. I then echo the result of the transform. Note that I do set unslash to false as I am using the content of my meta form directly.
Paragraphs aren't showing up, and whats more I can't even use html p tags! Any suggestions?