maximillianos - 12:11 pm on Dec 11, 2008 (gmt 0)

It is my belief and understanding that Google views subdomains as a separate site with weak ties to the main domain.

My reasoning is because I believe I heard Dr Cutts talk about it sometime in the past, but also because I've seen multiple results from one site show up in SERPS on the same page when subdomains were used. Granted this site I am referencing was abusing subdomains. And they eventually got booted from G. But the point is G deemed them as different sites in their results.

Now by design, content from a subdomain should be considerably different than the content on the main domain, hence the reason for having a subdomain in the first place. So in theory you shouldn't see them both in the top 10 for the same query too often. Which was one of the red flags behind the site that shall remain unspoken that got the boot.