Hot on the heels of yesterday's rumors, Yahoo and Tumblr have jointly announced a "definitive agreement" for the former to acquire the latter for $1.1 billion. The agreement makes it clear that Tumblr will be "independently operated as a separate business" with its own branding and line of development. A frankly worded press release says that this arms-length arrangement will help Yahoo "not to screw it up" and promises that the 300 mil
