Ok. That makes sense. The way our company would use it is having a microsite for specific, focused topics - large enough that warrant their own site.  They are clearly part of our overall brand, unlike the Disney properties example.  On each of these sites, there will almost always be a link back to the main/corporate website, usually in the footer.

Do you think having one or two links on every page pointing back to company.com would be sufficient to notify search engines that the two are associated, and ultimately give some search value to the subdomain hosted microsite from the main domain?

Are there any studies or evidence supporting any of this?

Based on this post from 2009, it's recommended in most situations to set up a microsite as a subdirectory as opposed to a subdomain. http://www.seomoz.org/blog/understanding-root-domains-subdomains-vs-subfolders-microsites.  The primary argument seems to be that the search engines view the subdomain as a separate entity from the domain and therefore, the subdomain doesn't benefit from any of the trust rank, quality scores, etc.  Rand made a comment that seemed like the subdomain could SOMETIMES inherit some of these factors, but didn't expound on those instances.

What determines whether the search engine will view your subdomain hosted microsite as part of the main domain vs. a completely separate site?  I read it has to do with the interlinking between the two.