Yahoo wants to become hip and cool again, and Tumblr is hip and cool. Tumblr is also huge and growing fast: It's one of a small handful of successful social media giants that also includes ...

What’s the price of “cool”? For Yahoo CEO Marissa Mayer, the number appears to be $1.1 billion. That’s how much cash Yahoo plans to pay for New York–based social-blogging platform Tumblr ...