That whole Yahoo buying Tumblr thing? That's a done deal. Yahoo CEO Marissa Mayer took to Yahoo's Tumblr account -- meta! -- to announce her excitement at the deal's close. "Today is an incredibly exciting day for Yahoo! and Tumblr," Mayer said. She reconfirmed Yahoo's commitment to running Tumblr as a separate entity, and announced a whole mess of new Tumblrs dedicated to various capacities of Yahoo (Search, Messenger, Mail, Sport
