Pre-orders and previews begin April 10, launches April 24.
Apple Seeds OS X Mavericks 10.9.1 Beta to Developers
Apple has seeded the first beta of OS X Mavericks 10.9.1 to developers. The release asks testers to focus on Mail, Graphics Drivers and VoiceOver, though there are no known issues with the release.
Earlier this month, Apple released a special update to Mavericks to address issues using Gmail with the Mail.app client built into the OS.
The update is available to registered developers through the OS X Developer Portal.