I wonder if PR0 links improve SERPs? If yes, what is the correlation between PR0 links and PR1 links in improving SERPs?
Link building is all about quality links... but as for PR0 links... well, I think they're fine if you've got the anchor text right... but don't ask me to give you a mathematical equation for it... at this level of SEO it's much about guess work and deciding whether an individual link fits your campaign...
Yes they do improve SERPs. But PR0 to PR1 weightage relation in SERPs is not really known. In general PR tends to influence SERPs depending on search parameters (for example competition on keyword). Also you can have link from PR1 page with unrelated content or PR0 link from page with related content. I personally think that in such case PR0 link from related-content is better than PR1 from unrelated. To sum up. There are several factors more important for position in SERPs than PR. Therefore weithage relations between links is unknown and of complex nature. Also as for now loads of low quality links are still better than few of high quality. From SEO point of view it's good to have as much high quality backlinks as you can collect, but also low quality backlinks (in high quantity) help.
All relevant links will increase your rankings. Moreover, a PR0 page as reflected on the Google toolbar might be a PR1, 2 or even more than 3 in Google's real live datacenter. Conclusion: They helps
As others mentioned PR does not matter anymore. Look for the relevancy of the site you are getting links from; thats all matter.
Thank you all very much for answers. One think suprised me. When my site got around 20-30 new backlinks from games toplists (all PR 2-4) my ranking in google for "free online games" keyword went from 23 to 6. I was really impressed about that. In the same time my site PR went from 0 to 4, so i`m not sure if these backlinks were effective in improving SERP or not.
As another DP member stated above, relevancy is somewhat more important than PR. For instance, I would take a PR0 inbound link on a relevant article from ezinearticles.com, over a PR4 non-relevant link to my website. If you look at one of my websites CancerFactsMD.com, you can see I rank #10 for cancer facts out of 5+ million results in Google. Notice I have only about 8 backlinks, but most are very relevant and high quality links (of course part of this is the fact that the keywords are in my url ).
As the others mentioned that the relevancy is more important than high pr, I agree with them. But it also matters having an inbound link to high pr sites and I've already prove that to my sites and blogs, so I suggest to use these techniques at the same time.
PR doesn't matter as much, but completely saying it doesn't matter altogether would mean you're missing out on something. They still take it into account and no matter how minor they still credit you for high inbound PR links. And while yes you can ignore them, I'm sure most of the people that are linked first page for whatever top keyword you're pushing for is taking both the PR of the incoming links into account as well as relevency (which yes is very important).
Whether it's a PR0 or a PR3 it will help if it's related to your site and content. The only thing a PR3 will do that a PR0 won't is give your site some of the PR juice (helping it gain a page rank on the next update)