updated 02:34 pm EDT, Thu August 21, 2014
Participants in the OS X Beta Program can now download a second public beta of OS X Yosemite via the Mac App Store. Changes are unlisted, but since it's following just a few days after the release of Developer Preview 6, it presumably incorporates that code's fixes and feature additions. Apple is believed to be building towards a final launch of Yosemite in October, which could mean one or two more public betas in the interim.
Apple is meanwhile also seeding a new beta of iTunes 12, identified as build 97. The v12 software is a substantial upgrade over its predecessor, with a "flattened" interface better suited to Yosemite, and streamlining designed to make browsing libraries and playlists easier. It also enables Family Sharing -- likewise featured in iOS 8 -- and a new Get Info window.