Markdown not affecting RSS feed

This works, but it causes the feed to become invalid. For example, in RSS2, the description element doesn’t allow p tags (or ul, etc.) — it expects plain text, not HTML.
Has anyone come up with a simple solution to this problem? There was a thread on wp-hackers that discusses this problem, but I didn’t see a solution that was agreed upon.
Thanks.

I noticed this as well. It was fixed by using full text instead of excerpt only feeds. I’m not entirely sure why, but I am happy.

Indeed, my solution renders the RSS invalid. I apologize.

Some kind of HTML stripping filter would do it, no?

I’ve been experimenting with this for the next release of PHP Markdown and here is what I plan to add:
add_filter('the_excerpt_rss', 'Markdown', 6);
add_filter('the_excerpt_rss', 'strip_tags', 100);
Try it and tell me what do you think.
— Michel Fortin

if you edit wp-rss, wp-rss2 and wp-atom you can add <[CDATA[ ….. ]]> around your content and it will validate again.
the 3 lines in wp-rss.php

25) <title><![CDATA[<?php the_title_rss() ?>]]></title>
29) <description><![CDATA[<?php the_excerpt_rss(get_settings('rss_excerp
t_length'), 2) ?>]]></description>
and
33) <description><![CDATA[<?php the_content_rss('', 0, '', get_settings(
'rss_excerpt_length'), get_settings('rss_encoded_html')) ?>]]></description>

the 5 lines in wp-rss2.php

22) <title><![CDATA[<?php the_title_rss() ?>]]></title>
31) <title><![CDATA[<?php the_title_rss() ?>]]></title>
38) <description><![CDATA[<?php the_excerpt_rss('', 2) ?>]]></descri
ption>
40) <description><![CDATA[<?php the_excerpt_rss(get_settings('rss_ex
cerpt_length'), 2) ?>]]></description>
and
41) <content:encoded><![CDATA[<?php the_content('', 0, '') ?>]]></co
ntent:encoded>

and the 4 lines in wp-atom.php

18) <title><![CDATA[<?php bloginfo_rss('name') ?>]]></title>
30) <title><![CDATA[<?php the_title_rss() ?>]]></title>
36) <summary type="text/html" mode="escaped"><![CDATA[<?php the_exce
rpt_rss(get_settings('rss_excerpt_length'), 2) ?>]]></summary>
38) <content type="text/html" mode="escaped" xml:base="<?php permali
nk_single_rss() ?>"><![CDATA[<?php the_content('', 0, '') ?>]]></content>

I really haven’t tested these changes much, but they validated for me and thats where I stopped.
I am using the enhanced textile2 plugin and had the same problem as you.

aint line breaks great.

I also noticed that Markdown isn’t rendered in the excerpts posted as trackbacks. Just for the record.