I have a business article blog which gained a PR of 3 in just 21 days of its launch. PR is actually calculated on a very complicated basis. Take the case of in.com. they dont have high quality or quantity back links. yet they are PR 6. You need inbound links for sure. try buying blog reviews. You can also ask for links from fellow webmasters
I never understand the whole PR is worthless attitude. Of course it is always dated, but it still provides some measure and gives you an idea as to if what you are doing is right. PR is part of a big puzzle, and while it in and of itself doesn't drive traffic, it is part of a greater scheme that can lead to great traffic.