linkpro.org link exchange and google

Hi, I recently got invited to this linkpro.org service, in which you need to give 5 outgoing links and receive 5 incoming links, my question is what does google think of such services, is there a penalty for using them?

Thanks

Google does not encourage us to "buy" or "sell" ads on our site to boost pagerank. I am not sure about link exchanges however. I do think they have a method for telling which are buying/selling. I will try and find the article about it

Originally Posted by http://searchengineland.com/071007-173841.php Now an official answer: yes. If you sell links, Google says it might drop your PR score, penalize you in the rankings or potentially ban your site altogether.