I maintain my company's website and can't seem to break the PR3 that we have had for quite some time. Meanwhile, I've created a couple of websites, as a favour, and it seems like one of them is already a PR3, without a lot of backlinks, only after being in existance for 9 months.
Recovery Force - PR3, been online for 8 years
Guelph Bible Chapel - PR1, been online for a couple of years
Two Roses Bed and Breakfast - PR3, been online for 9 months
I guess that the PR really doesn't matter. To me it is just a personal challenge, more than anything.