This is great. I see many important points in this declaration:

* animated gif and posted on tumblr : Yahoo gets it. Its CEO as well.

* "We will operate Tumblr independently" : I think this is exactly what everyone hoped, and what all big acquisition should be like (Facebook did that with Instagram and it's great!). That means NSFW will stay NSFW.

* "David Karp will remain CEO." The most qualified people to grow Tumblr are the people already in place. This is great, everyone's relieved.

I really think Yahoo's back in the game now. I would never have used yahoo before. Now hundred thousands of people are. And they are from the new generation.