The Wall Street Journal has an intersting take on The Yahoo buy out of Tumblr http://online.wsj.com/article/SB10001424127887324787004578493130789235150.html.
I am not sure if I agree with their point of view, I am inclined to think that there is a good chance that tumblr will become another geocities (anyone here old enough to remember that?), after Yahoo start tinkering with it.
One thing that this has borne out is that Marissa is a good strong leader at Yahoo and willing to make some big investments. Just what yahoo needed.