I suggest that you guys don't follow this method if you don't want your site to be penalized. Check out the op's latest post. I can't post any url yet, but here's the title of the thread. "my-websites-not-not-top-1000-any-keyword-i-received-gwt-message-also"
my website is not penalized due to this method. my website penalized due to private blog network posts which get deindexed and some sitewide links.
my website is not penalized due to this method. my website penalized due to private blog network posts which get deindexed and some sitewide links.