I've been using Google+ for that since the beta. If you remove all of the "hot", "recommended for you" and similar torrents of stupid from your circles, you can

I've been using Google+ for that since the beta. If you remove all of the "hot", "recommended for you" and similar torrents of stupid from your circles, you can create a vast circle of people with whom you can discuss politics, science and other things. My "politis" circle is a few hundred people, and a few thousands follow my politics (rabid infrared leftist) collections.