I modified wp-includes/default-filters.php as follows; I believe it has the effect of formatting a user’s profile description just like a post (but ignoring smilies):
Remove the line add_filter('pre_user_description', 'wp_filter_kses');
Add the lines:
add_filter('pre_user_description', 'wp_filter_post_kses');
add_filter('pre_user_description', 'wptexturize');
add_filter('pre_user_description', 'wpautop');
add_filter('pre_user_description', 'convert_chars');
add_filter('pre_user_description', 'balanceTags', 50);
The wp_filter_post_kses filter removes HTML prohibited in posts—it is less restrictive than wp_filter_kses.
