I have worked with a website in the past freedomist.com
This site gathers wordpress articles from multiple news source sites, and then republishes them. The company that runs this site has about 50 other sites that do the same thing. They post links to sites such as twitter and secondary wordpress sites.
Is this a moral way of increasing page ranking?
Is this against the terms of service with lets say Google?
This is called content scraping. Yes. It is not directly against Google terms, but definitely they don't like non-original content. Read Google's catch on this.
Also this is a violation of copyright, in most cases.
No, as per Sparky's answer. Besides that, it doesn't really help. Google has a lot of code in place to detect link farms and they will penalize such sites.
To boot, pagerank is overrated. Trustworthiness of the incoming links matters more. That is, you can have incoming links from pages with a high page rank but low trustworthiness and still not show high in the search ranking. In reverse you can have incoming links from low pagerank sites with high trustworthiness and score much better. It seems that pagerank is a second class citizen these days and google is relying more and more on other metrics to rate sites. Almost as if pagerank scoring is kept around to keep the SEO folk running in circles.
Duplicate content, especially content already published on another website, is exactly what Google, and you can assume the other search engines, are trying to eliminate from their indices. Doing it specifically to increase your rankings is also a big no-no. Not to mention republishing work already freely available on the Internet does nobody any good.
I'd say this is a waste of time and at best will only hurt you in the long run as Google takes action against sites like yours. My advice is to stop doing it.