I used to concerntrate a huge amout of time on PR a website i built for my dad http://www.getoninter.net has a PR of 3, and has done for some time.

I got the PR mainly from link building submitting links to other websites "simular" and link directories it took about 2 months to get the PR from 0 to 3. I did not know much about seo and visits to the site are about 35-45 per day.

My website http://www.xnitrorc.co.uk still does not have a PR but i concerntrate more on SEO, i still link build but seo and sef urls are the main thing i concerntrate on and my visits are about 65-120 per day and the website is less than 4 moths old. Compaired to my dads website wich is over a year old now.

I noticed the PR section in my google toolbar just 1 day was not there i got it back but had to go in settings. Its not as important as it used to be i still think it counts but not as much, but don't stop the link building, but try to target it more towards people and not search engines. By this i mean linking everywhere is never good but better for search engines and not people who may find you.