Preview at WWDC likely in June, followed by September launch.
Apple Seeds First iOS 8.1 Beta to Developers
Apple has also released a new Apple TV beta and Xcode 6.1 beta 3.
iOS 8.1 likely includes several bug fixes for issues in iOS 8, and it also likely includes support for Apple Pay, Apple's mobile payments service that is launching in October.
Along with iOS 8.1, Apple is also simultaneously working on iOS 8.2 and iOS 8.3, all of which are expected to add new functionality to the operating system.
iOS 8 has had a rough start, with Apple temporarily removing HealthKit ahead of the launch of iOS 8 and then releasing an unstable iOS 8.0.1 update that disabled the cellular and Touch ID service of many users. Apple released iOS 8.0.2 to fix the issue, but several other problems have come to light, including a bug that causes iCloud Drive documents to be deleted.