It's better not to bother too much about what google wants. These days yahoo is getting better by the day. I honestly feel that Google has another 2 years before it falls and mountain view gets calm. It already gets you the crappiest first page search results for any keyword. If you compare it with yahoo, you will notice the huge change in search results. Yahoo provides clean results and in fact most of my traffic these days originates from yahoo.
Directory site links are very valuable. I have noticed a significant influx of traffic from directories. But here again, not all directories can get you traffic. If you do some research, you can find some traffic directories which can help you get better results. And for the PR, I believe, the backlinks should be developed on a slow pace, rather than a sudden flurry of 600 links in a month. More importantly, they should be links from "similar" content sites. I mean, if my site is domain related and I get backlinks from cookery blogs, it wouldn't help my PR much. But if I develop links from domain forums, tech blogs and article directories, it would help immensely.
Btw, our virtuous google also sells PR8+ links in case anyone is interested. Thats why they invented the "PR" concept. Makes sense...

Quite naturally they have given themselves the PR10 ranking. Google is the most important site in the world.... they say so themselves.
Read here..
http://www.seobook.com/archives/002403.shtml
Google sells PR7 links for $10,000 a year.
http://www.conversionrater.com/index.php/2007/02/23/google-selling-pr7-links-for-10000/