This document introduces Yahoo! Open Strategy (Y!OS), which aims to provide a single platform (Yahoo! Application Platform or YAP) for developers to build applications that can run across Yahoo!, Yahoo!'s partners, and OpenSocial. It is authored by Josephj, a YDN Evangelist at Yahoo!, and provides his contact details. The document also mentions Y!OS will provide a unified experience for users across Yahoo!, its partners, and OpenSocial.