Media event set for September 9, launch likely ~10 days later.
Apple Begins Asking Developers to Turn On Family Sharing for iOS 8 and OS X Yosemite Apps
While Family Sharing is a significant addition to the App Store, the opt-in requirement for developers could see some declining to allow their apps to be shared amongst as many as six accounts with no extra charge.
To make your apps available as part of Family Sharing, agree to the updated iOS Paid Applications and/or Mac Paid Applications agreement in Contracts, Tax and Banking on iTunes Connect. To ensure that Family Sharing is also enabled for previously purchased apps, leave the appropriate checkbox selected on the agreements page.Family Sharing also allows families to share calendars, reminders, photos and locations. It also allows parents to monitor and approve downloads and purchases made by their children remotely. The feature is likely to get turned on and tested in the iOS 8 betas before going live when iOS 8 is available for the public later this year.