If you all can remember a couple years back when the SEO world was rocked when a person found a loop hole in Google's algorithm. This very intelligent person created a script that when the Google bot was recognized, the script would go out and make an infinite number of subdomains with relevant content and links pointing back to the main domain. As the Googlebot always has done, it followed the links and counted links from a subdomain as a IBL to the main domain. Hence this one persons domain had millions of IBLs. Google's official reply to this was "a bad data push" and they had adjusted their algorithm to fix this issue and the spammy sites were being removed automatically where as several members of the SEO world observed that the spammy sites were not being removed automatically, but were being removed by hand. Is anybody up to speed on what is Google's stand on subdomains crosslinking to the main domain? Does it still count as an IBL? Is this an okay thing to do or stray away from it?
No I am not asking if the flaw is still in the algorithm. I am just asking if crosslinking between subdomains and domains is okay in Google's eyes.