Does anyone have a plugin that could automatically tag custom post types in wordpress?

For a quick hack.

@ lines 74 and 91 of the plugin its making a SQL request where it’s limiting the results to posts only.

WHERE post_status="publish" AND post_type="post"

So, if you change that to include your custom postypes it should pick them up.

Or simply remove that SQL query and run a standard WP_Query query to return your posts in question.