Directory submission is a good way to generate one-way links.
Google gives little or no weight to Links from directories.
They virtually do
not count.
In my humble opinion, if you have to go out and submit to hundreds of directories just to 'try' and get PR, then there is something very wrong with your on-site SEO.
However, by submitting your site to
good directories and also submitting your articles to good
reputable article directories, this way people can find your site see that you have good solid content and naturally Link to you.
This is the only way it could help your PR.
Just merely having your site listed for a "link" purpose is not going to change anything, because as I said previously google virtually "dis-counts" directory links.