The importance of PageRank is misunderstood as are the benefits of backlinks.
PageRank basically determines how often and how deeply a site gets crawled, rather than how well content ranks (of course, frequent and deep crawling can lead to more content getting indexed which can, in turn, lead to ranking opportunities).
Backlinks are not essential for improved PageRank and are often detrimental.
The keys to better authority (PageRank):
- unique and substantive content
- liberal use of internal links
- focused theme
I launched three new sites Sept 2011, all of which were PR0 (two were brand new domain registrations).
As of Google's latest PR update all three were up to PR4. Some of the inner pages are at 1, 2, and 3.
And I should mention that I have done nothing in terms of building backlinks. All three sites have a combined total of 15 or 20 external backlinks.
Cheers