Since google’s latest shenanigans all my sites pretty much have pr4. Large established ones with huge traffic as well as little one page deals without any links.
My little linkless pages have much, much better exposure in the search engines than for instance Gamesandcasino.
Gamesandcasino is operating purely on branding, the little sites purely on SEO and I have one that is all PPC.
All these business models work. They all work differently, and none of them need any PR or links to work.
When I first put up the little seo pages, they had no pr at all for a couple of months. They still had good exposure in all the search engines. They also have little content to speak of.
As far as I am concerned, pr is for the birds anymore.
The whole scene is changing, and I get the most visitors now from MSN, then Yahoo, then Google. That is an average, it varies surprisingly between pages.