Astronomers report planet better than Earth!

[Matterplay1]

As for the short story about evolved descendants of self-replicating robots, that was by Poul Anderson and is called "Epilogue". I wish I had a copy, but I just went to look in my library and couldn't find a collection that had it. Memorable, though, and one of the inspirations for the OA Encyclopaedia Galactica article "Stanislaw" (the second inspiration is of course in Stanislaw Lem's book "The Invincible").

Here's a review of Anderson's story:
http://polaris93.livejournal.com/2745134.html