[wp-hackers] Ping and Privacy - misleading choices in Blog Visibility

[Otto]

The privacy option does four things:

1. Adds a <meta name='robots' content='noindex,nofollow' /> to all
pages (if they call wp_head, anyway).

2. Causes hits to robots.txt to send back:
User-agent: *
Disallow: /
This only works if a) WP is in the site root and b) no robots.txt
already exists.

3. Stops pings to ping-o-matic and any other RPC ping services
specified. This works by having the function privacy_ping_filter()
remove the sites to ping from the list. This filter is added by having
add_filter('option_ping_sites', 'privacy_ping_filter'); in the
default-filters. When the generic_ping function attempts to get the
ping_sites option, this filter blocks it from returning anything.

4. Hides the ping sites option entirely on the Options->writing page.