not a social network. Rather, it is a medium for discussing politics, entertainment and, more importantly, disseminating news.Twitter has come out several times now and said straight up - it is
It appears that Google News has caught on to this (not that Google is slow on the draw) and has begun testing a Twitter integration that shows news from your Twitter "friends" on your Google News page.
The feature allows you to "connect your Twitter account to see when people you follow are talking about the news." After adding your account, you will see "a list of updates containing news articles shared by the people you follow," according to the help document on the experimental feature. Only articles that can be found in Google News already will appear in the Twitter list - so it isn't really augmenting your Google News, but rather highlighting what you would see already with recommendations by friends.
The interesting part here is that you have two preference lists converging. First, you have the list of sources that constitutes Google News, and then you have the list of people you follow on Twitter. The friends feature only shows you where the two meet. This could be especially interesting if Google allows the friends list to show tweets according to what you're looking at on Google News. If I'm looking at local news, for instance, the friends column could help float to the top the most important news, according to what my friends are tweeting.
The pairing of the two seems like a match with much promise.