PR is eye candy for the webmaster. As you noted, it doesn't seem to have much impact on results. I have had the opportunity to listen to a few google reps and they always say don't worry about the PR. Personally, I believe it is more about the pages that are linking to you. Targeted links with specific keywords will result in showing up in the SERP's. But, then again. I don't work for google... They're the only ones who know for sure........

Brett