graeme_p - 5:38 am on Apr 17, 2013 (gmt 0)
When would you let Google crawl your admin pages?
Googlebot does not want to crawl the admin pages. It is complaining that the login page is crawlable: it is probably linked to from the rest of the site if its a typical WP theme.
THis problem is not a flaw is WP. Its a brute force attack that works on people who pick bad passwords. The only fault in WP was using the default username "admin".