My experience has been that yes, they help. I get more search results from pages where PR have anchor text in them rather than those with direct links at the bottom of the PR. A lot of times, sites will post the entirety of the PR on their site in the exact form they received it.
Yes, it completely possible, that they will fall completely down into the bowels of your site, but I still receive traffic from sites where my PR is still on the site, and in some cases up to a year after the release.
