Google Reader’s share tools on the other hand republish full blogs post for all to read without obtaining permission from blog publishers. So-called link blogs in Reader already break copyright and in a small way undermine blogs and content creators. If Google offers a comment service on shared items they are in effect creating copyright infringing blogs; after all they all have chronological entries and comments so they all look like blogs, even if they don’t provide a fully customizable CMS.-TechCrunch

A leaked Google video resulted in a post on Google Blogscoped . And plans of Google to introduce commenting system inside the shared reader items has sparked many posts including the one above by TechCrunch.

I doubt by aggregating and sharing the data Google/Users will be breaking any copyright rules. Feeds are given out for aggregating. If somebody is scared of their data being used should stop giving full feeds and go for partial feeds. They can even use the copyright notice or an url at the end of the post to make sure they get the credit. I am OK with people sharing my content in full/partial as long as they credit me and dont allow the search engines to index the aggregated content.

Coming back to comments on shared items. The system is similar to Facebook Notes App where you can import any feed ( but you should have the rights to import) and users can comment on it. These comments stay on Facebook and doesnt reach the original blogpost. If this is the concern of TechCrunch then I am with them. I would like Google to integrate the orginal blog comments into the reader. It could be either by extending the RSS/ATOM feed structure to include comments or simply linking to the original blog comment link. How about import/export comments functionality?

Further Reading:
There are many other reactions on the web about link blogging. You may want to read that of Scoble, greatest Google Reader Link Blogger.
On the same day comes another discussion between full tex feed v/s partial text feed at Problogger. In the debate are Gina Trapani of Lifehacker for partial feeds against Rick Klau from Feedburner supporting full text.