Google News is trying an experiment in participatory journalism. It will begin to post comments next to its links of news articles by anyone quoted or mentioned in those articles. Google claims that it will try to verify the identity of any such commenters (good luck), but it won't fact-check the comments before publishing them (as most newspapers and magazines do in their letters pages).
The play here for Google News is to add a layer of original content (conveniently produced by others, at no cost to Google) to the news links that make up its pages. Google News wants to become the aggregation point for all the news that's fit to link to, and offer a platform for interesting people (i.e., the subjects of news articles and blog posts) to expand on or grouse about the stories that mention them.
By allowing these selective comments, Google is inviting them into more of a conversation, and that's great. Although, many times, the best comments come from people not mentioned in an article, like competitors or just smart readers.
But what worries me more is that I'm not convinced that Google News is the best place to have those types of conversations in the first place. That sort of feedback makes a lot more sense on the Webpage that contains the actual news article or blog post in question. Otherwise, the comment is stripped from its context.
Most blogs, of course, already allow comments from pretty much anybody except spammers. Now, maybe more traditional news sites will be forced to do the same.