OS X Mavericks brought many improvements and changes to Macs, including contact and calendar syncing via iCloud. But Apple also removed the ability to sync either locally, without using iCloud. Many privacy concerned users were unhappy with being forced to have this data stored in Apple’s iCloud.
The latest beta build of iTunes. 11.1.6, which has been seeded to its employees, returns the ability to sync calendar and contacts locally, without the use of iCloud. While this could be reversed, it seems like a sensible thing for Apple to give users the option of avoiding iCloud if they want.
This build of iTunes comes with the beta of OS X 10.9.3, which itself has no major changes, but concentrates on bug fixes, especially regarding graphics and audio drivers.
The public release date for OS X 10.9.3 and iTunes 11.1.6 has not yet been announced.