More or less confirmed. Likely to be announced tomorrow.

So, Yahoo does not care about Tumblr’s Porn problem because it is not monetizable anyways? Remains to be seen if they would ignore it for the time being or proactively get rid of it.

Twitter acquired Posterous few months ago and is killing it. I guess the competition is back to between WordPress.com and Blogger.com.

No, I do not think Yahoo is going to shut down Tumblr. Posterous was puny in comparison. But I am guessing Tumblr folks would not be happy with the changes Yahoo would implement to make it profitable asap?