I wouldn't say
PR is useless at all. A few good links from relevant high
PR pages will make a significant difference in a site's placement. And links from PR0 pages, virtually none at all ...
I do agree that concentrating too much on
PR is not productive, but it is an important consideration in assessing the
SEO value of a link. For example, if you are considering submission to a directory with a paid review, and there are two categories that are relevant to your site, and one page has PR2 and the other PR3, with the same number of links, I would choose the PR3 category page.
Cheers, MJ