Apple has connected syncing with their built in database, Core Data,

Thanks for your article. One correction: Core Data is not a database. See Apple's documentation:

WHAT CORE DATA IS NOT "Core Data is not a database. Core Data provides an infrastructure for change management and for saving objects to and retrieving them from persistent storage. It is not in and of itself a database." http://developer.apple.com/documentation/Cocoa/Conceptual/CoreData/Articles/cdBasics.html#//appleref/doc/uid/TP40001650-DontLinkElementID10