The value of PR has been hotly debated ever since it first appeared.There are many who believe PR is at least as important to a website and IM as air is to a human, and others who do not worry about it.
Whilst the PR can affect the position in SERPs of a specific page, it does not always, and many PR0 pages can still list in the top 3 websites for any particular search term, even above those with a higher PR, because PR is only one of the many factors affecting the Google algortithm. PR does seem to be of more benefit to older content in getting higher SERPS though.
There are other instances when PR holds a higher importance, not directly to do with the SERPs. If, for instance, you wish to sell your website or domain, then the PR will be one of the most likely factors affecting price. (Alexa and Technorati rankings may also be taken into account). For attracting links to your site or blog, a high PR will always help. If you wish to sell advertising on your site, or be paid to post on blogs, then a higher PR will help you.
However, you need a long term strategy for all of the above that is not reliant on something which is entirely outside your control – Google pagerank updates. For all of the above instances, you need to have a business model which is based not on PR, but on the value of your site, your audience, and/or your skills, and you should work with companies/advertisers/purchasers etc who understand that the price of the website/advertising/blogging is not going to fluctuate every time your PR does.