Sorting out the best ways to monetize its site will be important for Tumblr as competition between it and other social networks like Facebook and Twitter heats up in mobile markets. On mobile, Tumblr's own user base has quadrupled over the past six months, the company said. The site has 54 million users total.
Just last week, for instance, Twitter announced a new program to let marketers target their ads to specific tweeted keywords.
Over the first week of the mobile ads program, the premiere placements will belong to Warner Brothers, which will showcase teaser trailers for the upcoming films "The Great Gatsby" and "The Hangover: Part III," and GE, which will spotlight its jet engines and locomotives, Tumblr said.