I do agree,Google cut down on backlinks/inbound links after the October 2007 updates.The reason it wanted every trader to use the adsense account.I tried discussing this in other forums too so that I was convinced regarding this action taken by Google but much too my disappointment I was criticized of spamming.At least I have a point now.In fact Google is suggesting the directories to trade links from now.
Here is the list of directories that Google has suggested.As for PR if you are optimizing primarily for Google it should be one of the most important things as it is because of the PR factor that Google has an added advantage over other major Search Engines like PR and backlinks.