MASHABLE - May 19 - Yahoo's board of directors has approved a $1.1 billion acquisition of blogging platform Tumblr. The deal is reportedly an all-cash acquisition. CEO Marissa Mayer was interested in the platform's younger-skewing user base, and had been in talks with the board about Tumblr for the last six weeks. Yahoo has purchased 10 startups since Mayer became CEO. Those companies include Stamped, a mobile app for finding and recommending activities, news browsing app Summly, and to-do list app Astrid. Tumblr has grown to a giant since its launch in 2007. It had ~67M unique visitors in April, according to Quantcast, and 18M of those came from mobile.