I think its just help you to generate bqacklinks links other wise its doesn't useful for you to increase your site pr.
What do you want to know ...?
--> helpful regarding possible boost of keywords?
There is no direct connection between High PR and high rankings. Therefore it could be helpful. Read these Tips & tricks on search engine optimization
Link exchanges do very little for SEO nowadays, but it's good to get your feet wet with other sites in your industry. It gets your name out there a bit. Don't worry about Google toolbar PageRank: it's meaningless. Link to sites that have good, quality content your audience would be interested in.
it would help from traffic point of view rather than pr.
if we link exchange with a site having 0 page rank.is it helpful or not?
i want to exchange with your sites. SNIP
No profit for your website. Always try to exchange your link with high pr websites.
you will get traffic towards your site even if you getting backlinks from the site having PR 0, but your PR wouldn't be increased.
Only way to time waste, only you can count back links but not PR