I have been trying out the custom post types for WordPress 3.0 Beta 2, I ran into a problem where i could not call the custom fields for posts i have assigned custom post type values.

I came up with this workaround for now until it is sorted.

function get_post_meta_custom($key, $single = false) {
 global $wpdb,$post;
 $answer = $wpdb->get_var($wpdb->prepare("SELECT meta_value FROM $wpdb->postmeta WHERE post_id = ".$post->ID." AND meta_key = '".$key."'"));
 return $answer;
}

Call it using the following. I use this inside on the single post inside the loop.

 if ( get_post_meta_custom('client_name', true) ) {echo get_post_meta_portfolio('client_name', true);    }