According to today's paper - Yahoo is paying $1.1 billion for Tumblr, in an effort to be more competitive with today's online markets. Maybe I haven't looked closely, but I find Tumblr unattractive to view. They're also impossible to work with if someone copies your content and puts it there.
A did a reasonably long blog post about all this yesterday, entitled "Yahoo Buying Tumblr ~ Tumblr Users Doomed". Perturbs me that I'm not allowed to say where, because I would really like to get the word out. Basically, it says you can expect Yahoo to treat their new Tumblr users as they treat what's left of their current Yahoo Voices users.