phranque - 4:00 am on May 3, 2012 (gmt 0)

http://support.google.com/webmasters/bin/answer.py?hl=en&answer=182072 [support.google.com]:

It's almost impossible to keep a web server secret by not publishing links to it.

http://support.google.com/webmasters/bin/answer.py?hl=en&answer=93708 [support.google.com]:

If you need to keep confidential content on your server, save it in a password-protected directory. Googlebot and other spiders won't be able to access the content. This is the simplest and most effective way to prevent Googlebot and other spiders from crawling and indexing content on your site.