No this isn't a fork. The post linked to zmanda, but you can find the old logo and a reference to 2.5.0 at http://www.amanda.org/
as usual. (I had no idea anyone actually liked that logo. Ten minutes with an image editor ten years ago, and it's still up there)
Amanda, as always, has been developed by whoever was willing to pick up the ball and run with it. Right now Zmanda is taking an active interest and contributing heavily back to the open source program. This is of course A Good Thing.