Last I heard, subdomains are treated as entirely separate sites by Google. Is this 100% true, or is there some search engine value in creating multiple related sites as subdomains of a common domain. For example, when making a site for every new XBox game that comes out - would giving each game it's own subdomain on a common established gaming domain allow the sites to jump past the sandbox more quickly? Or will I be forced to use subdirectories in order to achieve that?
Each subdomain is a separate site in Google's eyes. Which means the new ones will not have PR, authority, or any ranking power to pass on. It also means instead of internal links they'll be seen as external, which could be perceived as a link farm with what you're describing, depending on how far you take it. Words to the wise.
Subdomains are like brand new URLS to all the search engines, your better off using SubPages if you want to rank well and fast! Also avoid using /subfolder/ Use /page.html It ranks quicker and is better for SEO