Pasadena-based UberMedia, the newly renamed Twitter advertising and application provider, announced today that it has acquired Mixx. Mixx operates an online site which allows users to find social content. Financial terms of the acquisition were not disclosed. UberMedia said the acquisition would add to its family of applications, which now include UberTwitter, Twidroyd, and Echofon. UberMedia was, until Friday, known as PostUp, and headed by Idealab's Bill Gross. On Friday, PostUp said it was renaming itself UberMedia and had acquired Twitter client UberTwitter. The acquisition looks to be a part of a shift from a provider of Twitter-based ad services to one focused more on software applications for posting and reading Twitter and other social media content.