Basically they claim that the Circles of Google+ are inspired from the "Aspects" feature of Diaspora. Indeed, the function is very similar, although design like totally different. With the design, diaspora seems to take a little revenge, and nearly copy the status bar at the top of Google+.
However, it's good to see that Diaspora is still around. The interesting alternative is still in Alpha version. Despite some good coverage in online media, it didn't attract many users in the past. With the new design it might get a bit better. A kind of Twitter, Facebook and Tumblr integration is already working. And now keep hopes up for a Blogger.com integration.
It's still alive!