Sorry, I should have been more specific with my initial question. A high PR network is a privately owned network of websites each hosted on different class c ip addresses, with unique or private whois information, no website footprint between the sites (the html structure / layout of each site is different), and all reflecting good PR ranging from 3-7 with no historical large fluctuations in PR.
Owners of these networks will sell in-content homepage text link advertisements for a monthly fee ranging from $80 per month to $150 per month. A network usually consists of 35-55 websites and the link to your site using your targeted keyword would be made available on each site, usually with a unique content "blurb" on each website of about 150 words. If you stop payment, your link is removed from the entire network.
This is a very "black hat" technique to attain rankings but it appears to be working well for huge serp gains. Do you feel something like this, if done right, will be "busted" by Google? It's not fair to engage in ethical SEO and be circumvented by the black hatters!