WordPress filters for converting to and from Markdown using WP-Markdown plugin.

markdown_filters.php

<?php
// functions.php
if ( function_exists(wpmarkdown_markdown_to_html) && function_exists(wpmarkdown_html_to_markdown) ) {
  function markdown_to_html_func($content) {
    if ( function_exists('wpmarkdown_markdown_to_html') ) {
      return wpmarkdown_markdown_to_html($content);
    }
    return $content;
  }
  add_filter('markdown_to_html','markdown_to_html_func');
   
  function html_to_markdown_func($content) {
    if ( function_exists('wpmarkdown_html_to_markdown') ) {
      return wpmarkdown_html_to_markdown($content);
    }
    return $content;
  }
  add_filter('html_to_markdown','html_to_markdown_func');
}
?>

Its better to have it inside the wp-markdown core itself..... :D

@manojhl Stephen didn't see the need to put this into the core the last time I spoke with him about it.