OpenFeint. The goal is to "build a global ecosystem of distribution channels for game developers" through the combined efforts of the two companies, both of which have told Develop that OpenFeint's brand and CEO will remain intact following the completion of the purchase.
OpenFeint currently touts a user base of 75 million across Android and iOS, and even saw a huge spike in new users and OpenFeint-compatible game downloads over the Christmas holiday. Along with GREE's 25 million users in Japan, the two will have access to nearly 100 million people. And yes, we did that math all on our own.