Allen Hill says in Digitalpoint, if other websites are hosted on different IPs, you will definitely get good benefit for the main website in terms of search engine rankings and PR. However, content on each website which are pointed towards the main website also make a huge difference and hence the content should also be given some importance.
http://forums.digitalpoint.com/showthread.php?t=1469486
In an SEO Monopoly a company is attempting to control multiple sites on the front page of the search results. Each of these sites have some way of highlighting the parent company, usually, through the form of posts or text ads.
