vertical intregration is the basis by which most pre-war companies would aspire to operate. It means controlling the means to produce, distribute and control a single product. Ie: Sony is vertically intregrated as it makes the product, then promotes it and then sells it in its own stores. The stores themselves may be a "sony store" or a smaller subsidery company which sony have a share of. This means that sony are recouping their profits from every method possible.
I might not of explained that too well so heres the wiki explanation:
"In
microeconomics and
strategic management, the term
vertical integration describes a style of
ownership and control. Vertically integrated companies are united through a
hierarchy and share a common owner. Usually each member of the hierarchy produces a different
product or service, and the products combine to satisfy a common
need. It is contrasted with
horizontal integration. Vertical integration is one method of avoiding the
hold-up problem."
Vertically intregated domain names work in the same way, oftern with multiple names forwarding to the same site- such as this one.
John, your right google are VERY secretive about their Page Ranking system however certain aspects are common knowledge, others are easily worked out via reverse software engineering while some are just leaked the good old way!
The OSC forums are an excellent starting point for SEO optimization research and provide lots of genuine statements and links for one to trawl through.